<PAGE>   1
As filed with the Securities and Exchange Commission on September 10, 1998

                                                      Registration No.  33-73130
 
                      SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                                    SPSS Inc.

             (Exact name of registrant as specified in its charter)


              Delaware                                          36-2815480
    (State or other jurisdiction of                          (I.R.S.  Employer
      incorporation or organization                         Identification No.)

                            444 North Michigan Avenue
                             Chicago, Illinois 60611
               (Address, of Principal Executive Offices)(Zip Code)

                         The Second Amended and Restated
                     1995 Equity Incentive Plan of SPSS Inc.
                              (Full Title of Plan)

                                 Edward Hamburg
                       Executive Vice President, Corporate
                     Operations and Chief Financial Officer
                                    SPSS Inc.
                       233 South Wacker Drive, 11th Floor
                             Chicago, Illinois 60606
                     (Name and address of agent for service)
                                 (312) 651-3000
          (Telephone number, including area code, of agent for service)

                                   Copies To:
                          Lawrence R. Samuels, Esq.
                                 Ross & Hardies
                            150 North Michigan Avenue
                             Chicago, Illinois 60601
                                 (312) 558-1000

                         CALCULATION OF REGISTRATION FEE
<TABLE>
<CAPTION>
====================================================================================================================
                                                      Proposed
       Title of              Amount to be             maximum             457 (h) Proposed          Amount of
     Securities to          Registered (1)         offering price            aggregate         Registration fee (2)
     be registered                                 per share (2)         offering price (2)
<S>                            <C>                    <C>                  <C>                      <C>    

Common stock,                  1,119,750              $18.8125             $21,065,296.87           $6,214.26
$.01 par value
====================================================================================================================
</TABLE>





<PAGE>   2




(1)      The securities to be registered include a maximum of 1,119,750 shares
         issuable upon the exercise of options or as restricted shares under the
         Second Amended and Restated 1995 Equity Incentive Plan of SPSS Inc.
         assuming full participation of all employees under such plan.

(2)      Solely for purposes of calculating the registration fee, the offering
         price per share, the aggregate offering price and the amount of the
         registration fee have been computed in accordance with Rule 457(c)
         under the Securities Act of 1933, as amended. Accordingly, the price
         per share of Common Stock has been calculated to equal the average of
         the high and low prices of for a share of Common Stock, as reported on
         the Nasdaq National Market on September 3, 1998.



                                       2

<PAGE>   3


PROSPECTUS

1,119,750 Shares
SPSS INC.

Common Stock
($.01 Par Value)

     This Prospectus relates to the offer and sale of up to 1,119,750 shares of
the common stock, $.01 par value (the "Common Shares" or "Common Stock"), of
SPSS Inc. (the "Company"). The Common Shares may be offered by particular
stockholders of the Company (the "Selling Stockholders") from time to time in
transactions on the Nasdaq National Market, in negotiated transactions, or a
combination of such methods of sale, at fixed prices that may be changed, at
market prices prevailing at the time of sale, at prices related to such
prevailing market prices or at negotiated prices. The Selling Stockholders may
effect such transactions by the sale of the Common Shares to or through
broker-dealers, and such broker-dealers may receive compensation in the form of
discounts, concessions or commissions from the Selling Stockholders and/or the
purchasers of the Common Shares for whom such broker-dealers may act as agent or
to whom they may sell as principal, or both (which compensation to a particular
broker-dealer might be in excess of customary commissions). The Selling
Stockholders and any broker-dealer who acts in connection with the sale of
Common Shares hereunder may be deemed to be "underwriters" as that term is
defined in the Securities Act of 1933, as amended (the "Securities Act"), and
any commission received by them and profit on any resale of the Common Shares as
principal might be deemed to be underwriting discounts and commissions under the
Securities Act. See "Selling Stockholders" elsewhere in this Prospectus. The
Company will not receive any of the proceeds from the sale of the Common Shares
by the Selling Stockholders.

     The Company's Common Stock is traded and quoted on the Nasdaq National
Market under the symbol "SPSS." On September 9, 1998, the last sale price of
the Common Stock, as reported on the Nasdaq National Market, was $19 per
share.

     The Company will bear all expenses (other than underwriting discounts and
selling commissions, and fees and expenses of counsel or other advisors to the
Selling Stockholders) in connection with the registration of the shares of
Common Stock being offered hereby.

See "Selling Stockholders" elsewhere in this Prospectus.

SEE "RISK FACTORS" ON BEGINNING PAGE 7 FOR A DISCUSSION OF CERTAIN FACTORS THAT
SHOULD BE CONSIDERED IN CONNECTION WITH AN INVESTMENT IN THE COMMON STOCK.

THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION, NOR HAS THE SECURITIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

               The date of this Prospectus is September 10, 1998



                                       3


<PAGE>   4




                             AVAILABLE INFORMATION

     The Company is subject to the informational requirements of the Securities
Exchange Act of 1934, as amended (the "Exchange Act"), and in accordance
therewith files reports, proxy statements and other information with the
Securities and Exchange Commission (the "Commission"). Such reports, proxy
statements and other information filed by the Company, and the Registration
Statement of which this Prospectus forms a part, the exhibits and schedules
thereto and amendments thereof, may be inspected and copied at the public
reference facilities maintained by the Commission at 450 Fifth Street, N.W.,
Room 1024, Judiciary Plaza, Washington, D.C. 20549, and at the regional offices
of the Commission located at 7 World Trade Center, 13th Floor, New York, New
York 10048 and at Citicorp Center, 500 West Madison Street, Suite 1400, Chicago,
Illinois 60661-2511. Copies of such material can also be obtained from the
Public Reference Section of the Commission at 450 Fifth Street, N.W., Judiciary
Plaza, Washington, D.C. 20549 at prescribed rates. The Company's Common Stock is
quoted on the Nasdaq National Market, and therefore such reports, proxy
statements and other information can also be inspected at the offices of the
National Association of Securities Dealers, Inc., 1735 K Street, N.W., 3rd
Floor, Washington, D.C. 20006.

     Additional information regarding the Company and the shares offered hereby
is contained in the Registration Statement on Form S-8 and the exhibits thereto
(collectively, the "Registration Statement") filed with the Commission under the
Securities Act of 1933, as amended (the "Securities Act") in conjunction with
this Prospectus. As permitted by the rules and regulations of the Commission,
this Prospectus does not contain all of the information set forth in the
Registration Statement and the exhibits thereto, to which reference is hereby
made. Statements made in this Prospectus as to the contents of any contract,
agreement or other document referred to are not necessarily complete. With
respect to each such contract, agreement or other document filed as an exhibit
to the Registration Statement, reference is hereby made to the exhibit for a
more complete description of the matter involved, and each such statement will
be deemed qualified in its entirety by such reference. For further information
with respect to the Company and the shares of Common Stock offered hereby,
reference is hereby made to the Registration Statement, and the exhibits
thereto.

     SPSS, Categories, SYSTAT, Jandel Scientific, SigmaPlot, SigmaStat, Neural
Connection, Clear, Quancept, In2itive Technologies and In2Quest are registered
trademarks of the Company. SPSS/PC + SPSS Real Stats. Real Easy, QI Analyst,
BMDP, Jandel and Quantime are unregistered trademarks of the Company. allClear,
AnswerTree, TextSmart, SmartViewer and NewView are the subject of pending
applications for registration. This Prospectus also includes trade names and
marks of companies other than SPSS Inc.

                 INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

     The Company hereby incorporates by reference the following documents
previously filed with the Commission:


                                       4
<PAGE>   5


            (a) The Company's Annual Report on Form 10-K for the year ended 
     December 31, 1997;

            (b) The Company's Quarterly Report on Form 10-Q filed April 15, 1998
     for the fiscal quarter ended March 31, 1998.

            (c) The Company's Quarterly Report on Form 10-Q filed on August 14,
     1998 for the fiscal quarter ended June 30, 1998;

            (d) The description of the Company's Common Stock, $.01 par
     value (the "Common Stock"), contained in the Company's Registration
     Statement on Form 8-A filed with Commission on August 4, 1993, pursuant
     to Section 12 of the Exchange Act;

            (e) The description of the Company's Common Stock Purchase
     Rights, contained in the Company's Registration Statement on Form 8-A
     filed with the Commission on June 18, 1998; and

            (f) The Company's Proxy Statement, filed with the Commission
     on May 19, 1998, for its annual meeting of stockholders held on June
     17, 1998, except for the report of the Compensation Committee contained
     therein.

     All reports and other documents filed by the Company pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Exchange Act, subsequent to the date of this
Prospectus and prior to the termination of the offering shall be deemed to be
incorporated by reference into the Prospectus and Registration Statement and to
be a part hereof from the date of filing of such documents. Any statement
contained herein or in a document incorporated or deemed to be incorporated by
reference herein shall be deemed to be modified or superseded for purposes of
this Prospectus to the extent that a statement contained herein, or in any
subsequently filed document which also is or is deemed to be incorporated by
reference herein, modifies or supersedes such statement. Any such statement so
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Prospectus.

     The Company will provide, without charge, to each person (including any
beneficial owner) to whom this Prospectus is delivered, upon written or oral
request of such person, a copy of any and all of the information that has been
incorporated by reference in this Prospectus (not including exhibits to such
information unless such exhibits are specifically incorporated by reference into
such information). Such requests should be directed to: Edward Hamburg,
Executive Vice President, Corporate Operations, Chief Financial Officer and
Secretary, at the Company's principal executive offices at 233 South Wacker
Drive, 11th Floor, Chicago, Illinois 60606, telephone (312) 651-3000.



                                       5


<PAGE>   6


     UNLESS THE CONTEXT OTHERWISE REQUIRES, REFERENCES IN THIS PROSPECTUS TO
     "SPSS" AND THE "COMPANY" SHALL MEAN SPSS Inc. A DELAWARE CORPORATION, ITS
     ILLINOIS PREDECESSOR AND ITS SUBSIDIARIES, COLLECTIVELY; AND REFERENCES TO
     THE "COMMON STOCK" SHALL MEAN SPSS INC.'S COMMON STOCK, PAR VALUE $ .01 PER
     SHARE.

                                   THE COMPANY

GENERAL

     SPSS Inc. ("the Company") was incorporated in Illinois in 1975 under the
name "SPSS, Inc." and was reincorporated in Delaware in May 1993 under the name
"SPSS Inc." Unless the context otherwise requires, the terms "SPSS" and the
"Company" refer to SPSS Inc., a Delaware corporation, its Illinois predecessor
and its subsidiaries. SPSS is a multinational company that delivers reporting,
analysis and modeling software products, and whose primary markets are marketing
research, business analysis/data mining, scientific research and quality
improvement analysis. The Company develops, markets and supports an integrated
line of statistical software and other products that enable users to effectively
bring marketplace and enterprise data to bear on decision-making. The Company's
major products include SPSS for business and general applications, the Quantime
and In2itive family of products for market research, NewView for analytical
reporting, SigmaPlot and SYSTAT for scientific research, QI Analyst for quality
improvement and statistical process control, and allCLEAR for process
documentation and management. The primary users of the Company's software are
managers and data analysts in corporate settings, government agencies and
academic institutions. In addition to its widespread use in survey analysis,
SPSS software also performs other types of market research, as well as quality
improvement analyses, scientific and engineering applications and data
reporting. The current generation of SPSS Desktop products features a
windows-based point-and-click graphical user interface, sophisticated
statistical procedures, data access and management capabilities, report writing
and integrated graphics. The Company's products provide extensive analytical
capabilities not found in spreadsheets, database management systems or graphics
packages.

     In its 22 years as a corporation, SPSS has become a widely recognized name
in statistical software. The Company plans to leverage its current position to
take advantage of the increased demand for software applications that not only
provide ready access to the data that organizations collect and store, but also
enable users to systematically analyze, interpret and present such information
for use in decision-making. Management believes the ease-of-use of the Company's
current generation products, combined with the greater processing speed and
storage capacity of the latest desktop computers, has substantially expanded the
market for SPSS statistical software.

     In summer 1993, the Company completed an initial public offering (the
"IPO") of common stock, $.01 par value (the "Common Stock"). The Common Stock is
listed on the Nasdaq National Market under the symbol "SPSS". In early 1995, the
Company and certain selling stockholders (the "Selling Stockholders") sold
1,865,203 shares of Common Stock in a public offering.




                                       6
<PAGE>   7



Safe Harbor

     "Safe Harbor" Statement under the Private Securities Litigation Reform Act
of 1995: With the exception of historical information, certain matters discussed
in this Prospectus are forward-looking statements, within the meaning of Section
21E of the Securities Exchange Act, as amended, that involve risks and
uncertainties including, but not limited to, market conditions, competition and
other risks indicated in this document, and the Company's other filings with the
Securities and Exchange Commission that could cause actual results to vary
materially from the future results indicated in such forward-looking statements.
No assurance can be given that the future results covered by the forward-looking
statements will be achieved. Other factors could also cause actual results to
vary materially from the future results indicated in such forward-looking
statements.

                                  RISK FACTORS

     Fluctuations in Quarterly Operating Results. The Company's quarterly
operating results can be subject to fluctuation due to several factors,
including the number and timing of product updates and new product
introductions, delays in product development and introduction, purchasing
schedules of its customers, changes in foreign currency exchange rates, product
and market development expenditures, the timing of product shipments, changes in
product mix, timing, costs and effects of acquisitions and general economic
conditions. Because the Company's expense levels are to a large extent based on
its forecasts of future revenues, operating results may be adversely affected if
such revenues fall below expectations. Accordingly, the Company believes that
quarter-to-quarter comparisons of its results of operations may not be
meaningful and should not be relied upon as an indication of future performance.
The Company has historically operated with very little backlog because its
products are generally shipped as orders are received. As a result, revenues in
any quarter are dependent on orders shipped and licenses renewed in that
quarter. The Company has experienced a seasonal pattern in its operating results
with the fourth quarter typically having the highest operating income. For
example, excluding acquisition and other non-recurring charges, the percentage
of the Company's operating income realized in the fourth quarter was, 33% in
1995, 32% in 1996 and 35% in 1997. In addition, the timing and amount of the
Company's revenues are subject to a number of factors that make estimation of
operating results prior to the end of a quarter uncertain. A significant portion
of the Company's operating expenses are relatively fixed, and planned
expenditures are based primarily on revenue forecasts. More specifically, in the
fourth quarter, the variable profit margins on modest increases in sales volume
at the end of the quarter are significant. Should the Company fail to achieve
such fourth quarter revenue increases, net income for the fourth quarter and the
full year could be materially affected. Generally, if revenues do not meet the
Company's expectations in any given quarter, operating results will be adversely
affected. There can be no assurance that profitability on a quarterly or annual
basis can be achieved or sustained in the future.

     Dependence on a Single Product Category; Declining Sales of Certain
Products. The Company derives the major part of its product revenues from
licenses of statistical software. Accordingly, any decline in revenues from
licenses of the Company's statistical software, or 


                                       7


<PAGE>   8


reduction in demand for statistical software generally, could have a material
adverse effect on the Company.

     In recent years, SPSS, excluding the effects of the Quantime Limited and
In2itive Technologies A/S acquisitions, has experienced a significant shift in
the sources of its revenues. Historically, the Company derived a large portion
of its revenues from licenses of its mainframe and minicomputer ("Large
Systems") products. As a result of the general shift by computer users from
Large Systems to desktop computers, the Company experienced a decline in
revenues from Large Systems products in the last several years, although in 1996
sales of Large Systems products stabilized. Revenues from Large Systems licenses
declined from approximately $15.6 million in 1991 to $10.3 million in 1997,
while sales of desktop products increased from $14.7 million in 1991 to $81.3
million in 1997. Revenues from Large Systems licenses decreased from 1996 to
1997, by $400,000. Management is unable to predict whether the decline in Large
Systems licenses will continue or at what rate such licenses will decline.
Revenues from the Company's products for desktop computers ("Desktop products")
now account for nearly three-quarters of the Company's revenues and this
percentage may continue to increase.

     Risk Relating to Business Integration in Europe and Other Acquisitions. In
recent years, SPSS has made a significant number of acquisitions, including the
acquisition of businesses based outside of the United States. While SPSS has
substantial international operations, it faces challenges and business
integration issues with its September 1997 acquisition of Quantime and its
November 1997 acquisition of In2itive. Although persons whom the Company
believes are qualified and trained will continue to work with Quantime and
In2itive, there can be no assurance that Quantime or In2itive will be able to
retain these employees or hire suitable replacements in the event they should
leave the employ of SPSS. If the Company loses key personnel from Quantime or
In2itive or is unable to integrate Quantime's or In2itive's business into its
own effectively, the Company may experience a material adverse impact on its
financial condition. While SPSS believes that it has been successful in
integrating the acquisitions it has made in the past, there can be no assurance
that the recent acquisitions of Quantime or In2itive or future acquisitions will
be successfully integrated into SPSS.

     Rapid Technological Change. The computer software industry is characterized
by rapid technological advances, changes in customer requirements, frequent
product enhancements and new product introductions. The Company's future success
will depend upon its ability to enhance its existing products and introduce new
products that keep pace with technological developments, respond to evolving
customer requirements and achieve market acceptance. In particular, the Company
believes it must continue to respond quickly to users' needs for greater
functionality, improved usability and support for new hardware and operating
systems. Any failure by the Company to respond adequately to technological
developments and customer requirements, or any significant delays in product
development or introduction, could result in loss of revenues. In the past, the
Company has, on occasion, experienced delays in the introduction of new products
and product enhancements, primarily due to difficulties with particular
operating environments and problems with software provided by third parties. The
extent of these delays has varied depending upon the size and scope of the
project and the nature of the problems encountered. Such delays have most often
resulted from "bugs" encountered in working with new and/or beta-stage versions
of operating systems and other third party software, 



                                       8


<PAGE>   9

and bugs or unexpected difficulties in existing third party software which
complicate integration with the Company's software. From time to time, the
Company has discovered bugs in its products which are resolved through
maintenance releases or through periodic updates depending upon the seriousness
of the defect. There can be no assurance that the Company will be successful in
developing and marketing new products or product enhancements on a timely basis
or that the Company will not experience significant delays or defects in its
products in the future, which could have a material adverse effect on the
Company. In addition, there can be no assurance that new products or product
enhancements developed by the Company will achieve market acceptance or that
developments by others will not render the Company's products or technologies
obsolete or noncompetitive.

     International Operations. The Company's revenues from operations outside of
North America accounted for approximately 52%, 53% and 50% of the Company's net
revenues in 1995, 1996 and 1997 respectively. The Company expects that revenues
from international operations will continue to represent a large percentage of
its net revenues and that this percentage may increase, particularly as the
Company further "localizes" the SPSS product line by translating its products
into additional languages and expands its operations through acquisitions of
companies outside the United States. International revenues are subject to a
number of risks, including greater difficulties in accounts receivable
collection, longer payment cycles, exposure to currency fluctuations, political
and economic instability and the burdens of complying with a wide variety of
foreign laws and regulatory requirements. The Company also believes that it is
exposed to greater levels of software piracy in international markets because of
the weaker protection afforded to intellectual property in some foreign
jurisdictions. As the Company expands its international operations, the risks
described above could increase and, in any event, could have a material adverse
effect on the Company.

     Potential Volatility of Stock Price. There has been significant
volatility in the market prices of securities of technology companies, including
SPSS, and, in some instances, such volatility has been unrelated to the
operating performance of such companies. Market fluctuations may adversely
affect the price of the Common Stock. The Company also believes factors such as
announcements of new products by the Company or its competitors, quarterly
variations in financial results, recommendations and reports of analysts,
acquisitions and factors beyond the Company's control could cause the market
price of the Common Stock to fluctuate substantially.

     Reliance on Relationships with Third Parties. The Company licenses certain
software from third parties. Some of this licensed software is embedded in the
Company=s products, and some is offered as add-on products. If such licenses are
discontinued, or become invalid or unenforceable, there can be no assurance that
the Company will be able to develop substitutes for this software independently
or to obtain alternative sources in a timely manner. Any delays in obtaining or
developing substitutes for licensed software could have a material adverse
effect on the Company.

     In April 1998, the Company entered into a new non-exclusive, worldwide
agreement (the "Prentice Hall Agreement") with Prentice Hall, Inc. ("Prentice
Hall") under which Prentice Hall publishes and distributes selected student
version software packages and Company publications. 




                                       9



<PAGE>   10


As a result, the Company is dependent on Prentice Hall for the development and
support of the markets for student software and its publications. The failure of
Prentice Hall to perform its obligations under the Prentice Hall Agreement
adequately could have a material adverse effect on the Company. The Prentice
Hall Agreement has an initial term which expires in 2003, with an option to
renew for an additional five years under certain conditions.

     In January 1997, the Company entered into the Banta Global Turnkey Software
Distribution Agreement (the "Banta Agreement"), under which Banta Global Turnkey
("Banta") manufactures, packages, and distributes the Company's software
products to the Company's domestic and international customers and certain
international subsidiaries. The Banta Agreement has a three-year term and
automatically renews thereafter for successive periods of one year. Either party
may terminate the Banta Agreement for cause by written notice if the other
materially breaches its obligations. Such a termination notice for cause must
specifically identify the breach (or breaches) upon which it is based and will
be effective 180 days after the notice is received by the other party, unless
the breach(es) is (are) corrected during the 180 days. Either party may also
terminate the Banta Agreement on 180 days' notice for any other reason. If Banta
terminates the Banta Agreement other than for cause, it is required to assist
the Company in finding a new vendor. If Banta fails to perform adequately any of
its obligations under the Banta Agreement, the Company's operating results could
be materially adversely affected.

     Changes in Public Expenditures and Overall Economic Activity Levels. A
significant portion of the Company's revenues comes from licenses of its
products directly to foreign and domestic government entities. In addition,
significant amounts of the Company's revenues come from licenses to academic
institutions, Healthcare organizations and private businesses which contract
with or are funded by government entities. Government appropriations processes
are often slow, unpredictable and subject to factors outside the Company's
control. In addition, proposals are currently being made in certain countries to
reduce government spending. Reductions in government expenditures and
termination or renegotiation of government-funded programs or contracts could
have a material adverse effect on the Company. In addition, declines in overall
levels of economic activity could also have a material adverse impact on the
Company.

     Competition. The market for the statistical software is both highly
competitive and fragmented. The Company primarily competes with one general
statistical software provider which is larger and has greater resources than the
Company, as well as with numerous other companies offering statistical
applications software, many of which offer products focused on specific
statistical applications. The Company considers its primary worldwide competitor
to be the larger and better-financed SAS Institute ("SAS"), although the Company
believes that SAS's revenues are derived principally from products that are used
for purposes other than statistics and operate on large systems platforms.
StatSoft Inc., developers of the Statistica product ("Statistica"), Manugistics
Group, Inc., distributors of the Statgraphics Plus product ("Statgraphics"), and
Minitab, Inc. ("Minitab") are also competitors, although their annual revenues
from statistical products are believed to be considerably less than the revenues
of SPSS.


                                       10



<PAGE>   11

     In the future, SPSS may face competition from new entrants into the
statistical software market. The Company could also experience competition from
companies in other sectors of the broader market for data management, analysis
and presentation software, such as providers of spreadsheets, database
management systems, report writers and executive information systems. These
companies have added, or in the future may add, statistical analysis
capabilities to their products. Many of these companies have significant name
recognition, as well as substantially greater capital resources, marketing
experience and research and development capabilities than the Company. There can
be no assurance that the Company will have sufficient resources to make the
necessary investment in research and development and sales and marketing, or
that the Company will otherwise be able to make the technological advances
necessary to maintain or enhance its competitive position. The Company's future
success will also depend significantly upon its ability to continue to sell its
Desktop products, to attract new customers looking for more sophisticated or
powerful software and to introduce additional add-on products to existing
customers. There can be no assurance that the Company will be able to compete
successfully in the future.

     Dependence on Key Personnel. The Company is dependent on the efforts of
certain executives and key employees, including its President and Chief
Executive Officer, Jack Noonan. The Company's continued success will depend in
part on its ability to attract and retain highly qualified technical,
managerial, sales, marketing and other personnel. Competition for such personnel
is intense. There can be no assurance that the Company will be able to continue
to attract or retain such highly qualified personnel. No life insurance policies
are maintained on the Company's key personnel.

     Intellectual Property; Proprietary Rights. The statistical algorithms
incorporated in the Company's software are not proprietary. The Company believes
that the proprietary technology constituting a portion of the Company's software
determines the speed and quality of displaying the results of computations, the
connectivity of the Company's products with third party software and the ease of
use of its products. The Company's success will depend, in part, on its ability
to protect the proprietary aspects of its products. The Company attempts to
protect its proprietary software with trade secret laws and internal
nondisclosure safeguards, as well as copyright and trademark laws and
contractual restrictions on copying, disclosure and transferability that are
incorporated into its software license agreements. The Company licenses its
software only in the form of executable code, with contractual restrictions on
copying, disclosures and transferability. Except for licenses of its products to
users of Large System products and annual licenses of its Desktop products, the
Company licenses its products to end-users by use of a "shrink-wrap" license
that is not signed by licensees, as is customary in the industry. It is
uncertain whether such license agreements are legally enforceable. The source
code for all of the Company's products is protected as a trade secret and as
unpublished copyrighted work. In addition, the Company has entered into
confidentiality and nondisclosure agreements with its key employees. Despite
these restrictions, it may be possible for competitors or users to copy aspects
of the Company's products or to obtain information which the Company regards as
a trade secret. The Company has no patents, and judicial enforcement of
copyright laws may be uncertain, particularly outside of North America.
Preventing unauthorized use of computer software is difficult, and software
piracy is expected to be a persistent problem for the packaged software
industry. These problems may be particularly acute in international markets. In
addition, the 




                                       11


<PAGE>   12


laws of certain countries in which the Company's products are or may be licensed
do not protect the Company's products and intellectual property rights to the
same extent as the laws of the United States. Despite the precautions taken by
the Company, it may be possible for unauthorized third parties to reverse
engineer or copy the Company's products or obtain and use information that the
Company regards as proprietary. There can be no assurance that the steps taken
by the Company to protect its proprietary rights will be adequate to prevent
misappropriation of its technology.

     Although the Company's products have never been the subject of an
infringement claim, there can be no assurance that third parties will not assert
infringement claims against the Company in the future or that any such assertion
will not result in costly litigation or require the Company to obtain a license
to use the intellectual property of third parties. There can be no assurance
that such licenses will be available on reasonable terms, or at all. There can
also be no assurance that the Company's competitors will not independently
develop technologies that are substantially equivalent or superior to the
Company's technologies.

     Control by Existing Stockholders; Antitakeover Effects. As of August 10,
1998, the Company's executive officers and directors owned beneficially
approximately 21.5% of the outstanding shares of Common Stock. The Norman H. Nie
Revocable Trust Dated March 15, 1991 (the "Nie Trust") and affiliates of the Nie
Trust are entitled to nominate a director for inclusion in the management slate
for election to the Board if the Nie Trust owns no less than 12.5% of the
outstanding shares of Common Stock. As of August 10, 1998, the Nie Trust and
affiliates of the Nie Trust beneficially owned approximately 12.6% of the
outstanding shares of Common Stock. The Company's Certificate of Incorporation
and Bylaws contain a number of provisions, including provisions requiring an 80%
super majority stockholder approval of certain actions and provisions for a
classified Board of Directors, which would make the acquisition of the Company,
by means of an unsolicited tender offer, a proxy contest or otherwise, more
difficult or impossible.

     In June 1998, the Company adopted a Rights Agreement. The Board declared a
distribution of one Right for each share of Common Stock then outstanding. Each
share of Common Stock has an attached Right. The Rights are not exercisable or
detachable from the Common Stock. The Rights will become exercisable and
detachable only following the acquisition by a person or a group of 15 percent
or more of the outstanding Common Stock or following the announcement of a
tender or exchange offer for 15 percent or more of the outstanding Common Stock.

     The Rights will, if they become exercisable, permit the holders of the
Rights to purchase one share of Common Stock of the Company, or to exchange the
Rights for cash, property or other securities, if the Board permits. Where an
acquiring company effects a merger or other control transaction with the
Company, the Rights may also entitle the holder to acquire stock of the
acquiring company at 50 percent of its value. If a person or group acquires 15
percent or more of the Common Stock (or announces a tender or exchange offer for
15 percent or more of the Common Stock), the acquiring person=s or group=s
Rights become void. In certain circumstances, the Rights may be redeemed by the
Company at an initial redemption price of $.01 per Right.




                                       12



<PAGE>   13

     Shares Eligible for Future Sale. The Company has filed a Registration
Statement to permit transactions with respect to the shares of Common Stock
issued in connection with the Quantime and In2itive transactions.

     In addition to the shares of Common Stock which are outstanding, as of
August 10, 1998, there were vested options outstanding held by the executive
officers and directors to purchase and beneficially own approximately an
additional 798,373 shares of Common Stock, with an average exercise price of
$12.94 per share, and unvested options to purchase approximately an additional
210,637 shares of Common Stock. The Company has also established a stock
purchase plan available to employees of the Company, which permits employees to
acquire shares of Common Stock at the end of each quarter at 85% of the market
price of the Common Stock as of the day after the end of the quarter.

     No prediction can be made as to the effect, if any, that future sales, or
the availability of shares of Common Stock for future sales, will have on the
market price prevailing from time to time. Sales of substantial amounts of
Common Stock by the Company or by shareholders or the perception that such sales
may occur, could adversely affect prevailing market prices for the Common Stock.

     Year 2000. Many computer systems and applications currently use two digits
to define the applicable year. As a result, date-sensitive systems may recognize
the year 2000 as 1900 or not at all, which could cause miscalculations or system
failures. The Company has not completed its assessment of its computerized
systems to determine their ability to correctly identify the year 2000, but
currently believes that costs of addressing this issue will not have a material
adverse impact on the Company=s financial position. However, if the Company and
third parties upon which it relies are unable to address this issue in a timely
manner, it could result in a material financial risk to the Company. In order to
assure that this does not occur, the Company plans to devote all resources
required to resolve any significant year 2000 issues in a timely manner.

     Accumulated Deficit. The Company had an accumulated deficit of $4,797,000
as of June 30, 1998.



                                       13


<PAGE>   14

                              SELLING STOCKHOLDERS

     The following table sets forth the number of shares of Common Stock
beneficially owned by each Selling Stockholder as of August 10, 1998 the number
of shares of Common Stock that may be offered for the Selling Stockholder's
account and based on the number of shares of Common Stock beneficially owned as
of August 10, 1998 the percentage of the shares of Common Stock to be
beneficially owned by such Selling Stockholder if they elect to sell all of
their Shares of Common Stock that are available for sale.

<TABLE>
<CAPTION>
                                                                                          Shares of Common
                                            Shares of                                       Stock To Be
                                           Common Stock          Maximum Number of       Beneficially Owned
                                        Beneficially Owned       Shares Available        Assuming Sale of All
               Name of                         As of                To Be Sold           Shares Available For
         Selling Stockholder              August 10, 1998         Pursuant Hereto         Sale Hereunder (1)
         -------------------              ---------------         ---------------         ------------------
 
                                                                                          Number      Percent
                                                                                          ------      -------
<S>                                          <C>                       <C>                <C>           <C>
Jack Noonan (2)                                229,674                 50,000              179,674       1.9%

Edward Hamburg (3)                             131,357                 25,000              106,357       1.2%

Louise E.  Rehling (4)                         102,355                 25,000               77,355        *

Susan Phelan (5)                                95,907                 25,000               70,907        *

Mark Battaglia (6)                             105,340                 25,000               80,340        *

Ian Durell (7)                                  50,624                 25,000               25,624        *

Norman Nie (8)                               1,140,448                 10,000            1,130,448      12.4%

Merritt Lutz (9)                                28,204                 10,000               18,204        *

Bernard Goldstein (10)                          44,315                 10,000               34,315        *

Fredric Harman (11)                              8,919                 10,000                 --          *

Michael Blair (12)                               2,918                 10,000                 --          *

</TABLE>

*    The percentage of shares beneficially owned does not exceed 1% of the 
     class.

(1)  Based upon the number of Shares of Common Stock outstanding on August
     10, 1998. Assumes all stock that may be offered pursuant to this Prospectus
     is sold, and no other shares beneficially owned by the Selling Stockholders
     are sold.

(2)  Includes 221,508 shares subject to options exercisable within 60 days.  
     Mr. Noonan is President, Chief Executive Officer and Director of the 
     Company.




                                       14



<PAGE>   15


(3)  Includes 121,357 shares subject to options exercisable within 60 days. 
     Mr. Hamburg is Executive Vice President, Corporate Operations, Chief
     Financial Officer and Secretary of the Company.

(4)  Includes 98,290 shares subject to options exercisable within 60 days.
     Includes 200 shares held in the Stella S. Hechtman Trust (the ATrust@). Ms.
     Rehling is the Trustee and has the voting and investment power over the 200
     shares held in the Trust. She disclaims beneficial ownership of these
     shares. Ms. Rehling is Executive Vice President, Product Development of the
     Company.

(5)  Includes 93,921 shares subject to options exercisable within 60 days.
     Ms. Phelan is Executive Vice President, Domestic Sales and Services of the
     Company. Previously, Ms. Phelan was Executive Vice President SPSS Products
     and Services.

(6)  Includes 104,957 shares subject to options exercisable within 60 days.  
     Mr. Battaglia is Executive Vice President, Corporate Marketing of the
     Company.

(7)  Mr. Durrell is the beneficial owner of these shares which consist solely 
     of 50,624 shares subject to options exercisable within 60 days held of
     record by Valletta Investments. Mr. Durrell is Executive Vice President,
     SPSS Market Research. Previously Mr. Durrell was Executive Vice President,
     International of the Company.

(8)  Includes 78,815 shares subject to options exercisable within 60 days;
     110,433 shares held of record by the Norman and Carol Nie Foundation, Inc.
     (the "Nie Foundation"); and 951,200 shares held by the Nie Trust. Professor
     Nie shares voting and investment power over the 110,433 shares held by the
     Nie Foundation with Carol Nie. Dr. Nie is Chairman of the Board of the
     Company.

(9)  Includes 8,871 shares subject to options exercisable within 60 days.
     Mr. Lutz is a Director of the Company. Mr. Lutz shares voting power over 
     6,000 of these shares with Mary C. Lutz.

(10) Includes 8,871 shares subject to options exercisable within 60 days.  
     Mr. Goldstein is a Director of the Company.

(11) Includes 8,871 shares subject to options exercisable within 60 days.  
     Mr. Harman is a Director of the Company.

(12) Includes 2,918 shares subject to options exercisable within 60 days.  
     Mr. Blair is a Director of the Company.


                                 USE OF PROCEEDS

     The Company will not receive any proceeds from the registration or sale of
the shares of Common Stock offered hereby.




                                       15



<PAGE>   16

                        DIVIDEND POLICY AND RESTRICTIONS

     The Company has never declared any cash dividends or distributions on its
capital stock and does not anticipate paying cash dividends in the foreseeable
future. The Company currently intends to retain its future earnings to fund
ongoing operations and future capital requirements of its business.

                              PLAN OF DISTRIBUTION

     The Common Stock may be offered by the Selling Stockholders from time to
time in transactions on the Nasdaq National Market, in negotiated transactions,
or a combination of such methods of sale, at fixed prices that may be changed,
at market prices prevailing at the time of sale, at prices related to such
prevailing market prices or at negotiated prices. The Selling Stockholders may
effect such transactions by the sale of the Common Stock to or through
broker-dealers, and such broker-dealers may receive compensation in the form of
discounts, concessions or commissions from the selling Stockholders and/or the
purchasers of the Common Stock for whom such broker-dealers may act as agent or
to whom they may sell as principal, or both (which compensation to a particular
broker-dealer might be in excess of customary commissions). The Selling
Stockholders and any broker-dealer who acts in connection with the sale of
Common Stock hereunder may be deemed to be "underwriters" as that term is
defined in the Securities Act, and any commission received by them and profit on
any resale of the Common Stock as principal might be deemed to be underwriting
discounts and commissions under the Securities Act.

     No prediction can be made as to the effect, if any, that future sales, or
the availability of shares of Common Stock for future sales, will have on the
market price prevailing from time to time. See "RISK FACTORS -- Shares Eligible
for Future Sale" elsewhere in this Prospectus.

                                  LEGAL MATTERS

     The validity of the shares of Common Stock is being passed upon for the
Company by Ross & Hardies, Chicago, Illinois.

                                     EXPERTS

     The consolidated financial statements of SPSS Inc. and subsidiaries as of
December 31, 1997 and 1996 and for each of the three years in the period ended
December 31, 1997, have been incorporated by reference herein from the Companys
Annual Report on Form 10-K for the year ended December 31, 1997 in reliance upon
the report of KPMG Peat Marwick LLP, independent certified public accountants,
incorporated by reference herein, and upon the authority of said firm in
accounting and auditing.

     With respect to the unaudited interim financial information for the periods
ended March 31, 1998 and 1997, and June 30, 1998 and 1997, incorporated by
reference herein, the independent certified public accountants have reported
that they applied limited procedures in accordance with professional standards
for a review of such information. However, their



  


<PAGE>   17

                                   

separate reports included in the Company's quarterly reports on Form 10-Q for
the quarters ended March 31, 1998 and June 30, 1998, and incorporated by
reference herein, states that they did not audit and they do not express an
opinion on that interim financial information. Accordingly, the degree of
reliance on their report on such information should be restricted in light of
the limited nature of the review procedures applied. The accountants are not
subject to the liability provisions of section 11 of the Securities Act of 1933
for their report on the unaudited interim financial information because that
report is not a Areport@ or a Apart@ of the registration statement prepared or
certified by the accountants within the meaning of sections 7 and 11 of the Act.


                                       17



<PAGE>   18


NO DEALER, SALESMAN OR OTHER PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION
OR TO MAKE ANY REPRESENTATIONS OTHER THAN THOSE CONTAINED IN THIS PROSPECTUS IN
CONNECTION WITH THE OFFER MADE BY THIS PROSPECTUS AND, IF GIVEN OR MADE, SUCH
INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED
BY THE COMPANY. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR ANY SALE MADE
HEREUNDER SHALL UNDER ANY CIRCUMSTANCES CREATE AN IMPLICATION THAT THERE HAS
BEEN NO CHANGE IN THE AFFAIRS OF THE COMPANY SINCE THE DATE HEREOF. THIS
PROSPECTUS DOES NOT CONSTITUTE AN OFFER OR SOLICITATION BY ANYONE IN ANY
JURISDICTION IN WHICH SUCH OFFER OR SOLICITATION IS NOT AUTHORIZED OR IN WHICH
THE PERSON MAKING SUCH OFFER OR SOLICITATION IS NOT AUTHORIZED OR IN WHICH THE
PERSON MAKING SUCH OFFER OR TABLE OF CONTENTS SOLICITATION IS NOT QUALIFIED TO
DO SO OR TO ANYONE TO WHOM IT IS UNLAWFUL TO MAKE SUCH OFFER OR SOLICITATION.

                                TABLE OF CONTENTS
<TABLE>
<CAPTION>
                                                                           Page
<S>                                                                         <C>
Available Information....................................................... 4
Incorporation of Certain Documents by Reference............................. 4
The Company................................................................. 6
Risk Factors................................................................ 7
Selling Stockholders........................................................15
Use of Proceeds.............................................................16
Dividend Policy and Restrictions............................................17
Plan of Distribution........................................................17
Legal Matters...............................................................17
Experts.....................................................................17
</TABLE>

1,119,750 Shares

SPSS INC.

COMMON STOCK
($.01 PAR VALUE)


Prospectus

Dated September 10, 1998



                                       18



<PAGE>   19

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Certain Documents by Reference

     SPSS Inc. (the "Company") hereby incorporates by reference the
following documents previously filed with the Securities and Exchange Commission
(the "Commission"):

         (a)      The Company's Annual Report on Form 10-K for the year ended 
     December 31, 1997;

         (b)      The Company's Quarterly Report on Form 10-Q filed April 15, 
     1998 for the fiscal quarter ended March 31, 1998;

         (c)      The Company's Quarterly Report on Form 10-Q filed on August
     14, 1998 for the fiscal quarter June 30, 1998;

         (d)      The description of the Company's Common Stock, $.01 par value
     (the "Common Stock"), contained in the Company's Registration Statement on 
     Form 8-A filed with Commission on August 4, 1993, pursuant to Section 12 
     of the Exchange Act;

         (e)      The description of the Company's Common Stock Purchase Rights,
     contained in the Company's Registration Statement on Form 8-A filed with 
     the Commission on June 18, 1998; and

         (f)      The Company's Proxy Statement, filed with the Commission on 
     May 19, 1998, for its annual meeting of stockholders held on June 17, 1998,
     except for the report of the Compensation Committee contained therein.

     All documents subsequently filed by the Company pursuant to Sections 13(a),
13(c), 14 and 15(d) of the Exchange Act, subsequent to the effective date of the
Registration Statement and prior to filing of a post-effective amendment to the
Registration Statement which indicates that all securities offered have been
sold or which deregisters all securities then remaining unsold, shall be deemed
incorporated by reference in the Registration Statement and to be a part hereof
from the date of filing of such documents.

Item 4.  Description of Securities

         Not applicable.

Item 5.  Interests of Named Experts and Counsel

         Not applicable.

Item 6.  Indemnification of Officers and Directors



                                       19



<PAGE>   20

     Delaware General Corporation Law. The Company has statutory authority to
indemnify its officers and directors. The applicable provisions of the General
Corporation Law of the State of Delaware (the "GCL") state that, to the extent
such person is successful on the merits or otherwise, a corporation may
indemnify any person who was or is a party or who is threatened to be made a
party to any threatened, pending or completed action, suit or proceeding,
whether civil, criminal, administrative or investigative (other than an action
by or in the right of the corporation), by reason of the fact that he is or was
a director, officer, employee or agent of the corporation or is or was serving
at the request of the corporation as a director, officer, employee or agent of
another corporation, partnership, joint venture, trust or other enterprise
("such Person"), against expenses (including attorneys' fees), judgments, fines
and amounts paid in settlement, actually and reasonably incurred by such Person,
if he acted in good faith and in a manner he reasonably believed to be in or not
opposed to the best interests of the corporation and with respect to any
criminal action or proceeding, had no reasonable cause to believe his conduct
was unlawful. In any threatened pending or completed action by or in the right
of the corporation, a corporation also may indemnify any such Person for costs
actually and reasonably incurred by him in connection with that action's defense
or settlement, if he acted in good faith and in a manner he reasonably believed
to be in or not opposed to the best interests of the corporation; however, no
indemnification shall be made with respect to any claim, issue or matter as to
which such Person shall have been adjudged to be liable to the corporation,
unless and only to the extent that a court shall determine that such indemnity
is proper.

Under the applicable provisions of the GCL, any indemnification shall be made by
the corporation only as authorized in the specific case upon a determination
that the indemnification of the director, officer, employee or agent is proper
in the circumstances because he has met the applicable standard of conduct. Such
determination shall be made:

     (1) By the Board of Directors by a majority vote of a quorum consisting of
         directors who are not parties to such action, suit or proceeding; or

     (2) If such a quorum is not obtainable or, even if obtainable, a quorum of
         disinterested directors so directs, by independent legal counsel in a 
         written opinion; or

     (3) By the affirmative vote of a majority of the shares entitled to
         vote thereon.

The Company's Certificate of Incorporation provides for indemnification to the
full extent permitted by the laws of the State of Delaware against and with
respect to threatened, pending or completed actions, suits or proceedings
arising from or alleged to arise from, a party's actions or omissions as a
director, officer, employee or agent of the Company or of any subsidiary of the
Company or of any other corporation, partnership, joint venture, trust or other
enterprise which he has served in such capacity at the request of the Company if
such acts or omissions occurred or were or are alleged to have occurred, while
said party was a director or officer of the Company.

     The Company maintains a director and officer liability insurance policy
which indemnifies directors and officers for certain losses arising from a claim
by reason of a wrongful 



                                       20


<PAGE>   21



act, as defined, under certain circumstances where the Company does not provide
indemnification.

Item 7.  Exemption from Registration Claimed.

         Not applicable.

Item 8.  Exhibits.  
<TABLE>
<CAPTION>
                                                                  Incorporation
                                                                       by
Exhibit                                                            Reference
Number   Description of Document                                 (if applicable)
<S>      <C>                                                           <C>

4.1      Loan Agreement                                                 *

5.1      Opinion of Ross & Hardies regarding legality of shares 
         of Common Stock

15.1     Letter re: Unaudited Interim Financial Information

23.1     Consent of KPMG Peat Marwick LLP

23.2     Consent of Ross & Hardies

24.1     Power of Attorney                                             ***

</TABLE>

*        Previously filed with SPSS' Form 10-Q for the Quarterly Period Ended 
         on June 30, 1998 
***      Included in signature pages.

 (b)     The Company did not file any reports on Form 8-K during fiscal year

Item 9.  Undertakings.

         (a)      The undersigned Registrant hereby undertakes:

                  (1)      To file, during any period in which offers or sales 
                           are being made, a post-effective amendment to this 
                           Registration Statement:

                           (i)     To include any prospectus required by 
                                   Section 10(a)(3) of the Securities Act of 
                                   1933;

                           (ii)    To reflect in the prospectus any facts or 
                                   events arising after the effective date of
                                   this Registration Statement (or the most
                                   recent post-effective amendment thereof)
                                   which, individually or in the aggregate,
                                   represent a fundamental change in the
                                   information set forth in this Registration
                                   Statement. Notwithstanding the foregoing, any
                                   increase or
                                            




                                       21



<PAGE>   22



                                  decrease in volume of securities offered (if
                                  the total dollar value of securities offered
                                  would not exceed that which was registered)
                                  and any deviation from the low or high end of
                                  the estimated maximum offering range may be
                                  reflected in the form of prospectus filed with
                                  the Commission pursuant to Rule 424(b) if, in
                                  the aggregate, the changes in volume and price
                                  represent no more than a 20% change in the
                                  maximum aggregate offering price set forth in
                                  the "Calculation of Registration Fee" table in
                                  the effective Registration Statement.

                          (iii)   To include any material information with 
                                  respect to the plan of distribution not
                                  previously disclosed in this Registration
                                  Statement or any material change to such
                                  information in this Registration Statement;

                          provided, however, that paragraphs (a)(1)(i) and
                          (a)(1)(ii) do not apply if the registration statement
                          is on Form S-3, Form S-8 or Form F-3, and the
                          information required to be included in a
                          post-effective amendment by those paragraphs is
                          contained in periodic reports filed by the Registrant
                          pursuant to Section 13 or Section 15(d) of the
                          Securities Exchange Act of 1934 that are incorporated
                          by reference in this Registration Statement.

                 (2)      That, for the purpose of determining any liability 
                          under the Securities Act of 1933, each such
                          post-effective amendment shall be deemed to be a new
                          registration statement relating to the securities
                          offered therein, and the offering of such securities
                          at that time shall be deemed to be the initial bona
                          fide offering thereof.

                 (3)      To remove from registration by means of a 
                          post-effective amendment any of the securities being
                          registered which remain unsold at the termination of
                          the offering.

        (b)      The undersigned Registrant hereby undertakes that for purposes 
                 of determining any liability under the Securities Act of 1933,
                 each filing of the Registrant's annual report pursuant to
                 Section 13(a) or Section 15(d) of the Securities Exchange Act
                 of 1934 (and, where applicable, each filing of an employee
                 benefit plan's annual report pursuant to Section 15(d) of the
                 Securities Exchange Act of 1934) that is incorporated by
                 reference in this Registration Statement shall be deemed to be
                 a new registration statement relating to the securities offered
                 herein and the offering of such securities at that time shall
                 be deemed to be the initial bona fide offering thereof.

        (c)      The undersigned Registrant hereby undertakes that, insofar as 
                 indemnification for liabilities arising under the Securities 
                 Act of 1933 may 






                                       22




<PAGE>   23



         be permitted to directors, officers and controlling persons of the
         registrant pursuant to the foregoing provisions, or otherwise, the
         registrant has been advised that in the opinion of the Securities and
         Exchange Commission such indemnification is against public policy as
         expressed in the Act and is, therefore, unenforceable.  In the event
         that a claim for indemnification against such liabilities (other than
         the payment by the registrant of expenses incurred or paid by a
         director, officer or controlling person of the registrant in the
         successful defense of any action, suit or proceeding) is asserted by
         such director, officer or controlling person in connection with the
         securities being registered, the registrant will, unless in the opinion
         of its counsel the matter has been settled by controlling precedent,
         submit to a court of appropriate jurisdiction the question of whether
         such indemnification by it is against public policy as expressed in the
         Act and will be governed by the final adjudication of such issue.


                                       23




<PAGE>   24


                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Chicago, State of Illinois, on September 10, 1998.

                                     SPSS INC.


                                     By: /s/ Jack Noonan 
                                         -------------------------------------  
                                         Jack Noonan
                                         President and Chief Executive Officer

                                POWER OF ATTORNEY

     Each person whose signature appears below hereby constitutes and appoints
Jack Noonan and Edward Hamburg, and each of them, the true and lawful
attorneys-in-fact and agents of the undersigned, with full power of substitution
and resubstitution, for and in the name, place and stead of the undersigned, in
any and all capacities, to sign any and all amendments (including post-effective
amendments) to this Registration Statement, and to file the same, with all
exhibits thereto, and other documents in connection therewith, with the
Securities and Exchange Commission, and hereby grants to such attorneys-in-fact
and agents, and each of them, full power and authority to do and perform each
and every act and thing requisite and necessary to be done in furtherance of the
foregoing, as fully to all intents and purposes as the undersigned might or
could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents, or any of them, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on September 10, 1998.

Signature                      Title(s)


/s/ Norman H. Nie              Chairman of the Board
-----------------------
Norman H.  Nie


/s/ Jack Noonan                President, Chief Executive Officer
-----------------------        and Director
Jack Noonan                         


/s/ Edward Hamburg             Executive Vice President, Corporate Operations,
-----------------------        Chief Financial Officer and Secretary
Edward Hamburg                 


/s/ Robert Brinkmann           Controller and Assistant Secretary
-----------------------        (Chief Accounting Officer)
Robert Brinkmann        



                                       24



<PAGE>   25


/s/ Bernard Goldstein                       Director
-------------------------
Bernard Goldstein


/s/ Fredric W. Harman                       Director
-------------------------
Fredric W. Harman


/s/ Merritt Lutz                            Director
-------------------------
Merritt Lutz


/s/ Michael Blair                           Director
-------------------------
Michael Blair



                                       25





<PAGE>   26


                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549




                               EXHIBITS FILED WITH

                 THE POST EFFECTIVE AMENDMENT NO. 1 ON FORM S-8

                             REGISTRATION STATEMENT

                                      UNDER

                           THE SECURITIES ACT OF 1933



                                    SPSS INC.
















<PAGE>   27



                                   SPSS INC.





                                                                    Location of
                                                                    Document in
                                                                    Sequential
                                                                     Numbering
Exhibit No.       Description                                         System 

    5.1           Opinion of Ross & Hardies regarding legality of 
                  shares of Common Stock
                 

   15.1           Letter re: Unaudited Interim Financial Information.

   23.1           Consent of KPMG Peat Marwick LLP

   23.2           Consent of Ross & Hardies (contained in opinion filed as 
                  Exhibit 5.1)

   24.1           Power of Attorney (contained in signature pages)
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 71033}]
{"company-data": {"conformed-name": "SPSS INC", "cik": "0000869570", "assigned-sic": "7372", "irs-number": "362815480", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-63167", "film-number": "98707151"}, "business-address": {"street1": "444 NORTH MICHIGAN AVE", "city": "CHICAGO", "state": "IL", "zip": "60611", "phone": "3123292400"}, "mail-address": {"street1": "444 N MICHIGAN AVE", "city": "CHICAGO", "state": "IL", "zip": "60611"}}
1
As filed with the Securities and Exchange Commission on September 10, 1998

                                                      Registration No.  33-73130
 
                      SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      Under
                           The Securities Act of 1933

                                    SPSS Inc.

             (Exact name of registrant as specified in its charter)

              Delaware                                          36-2815480
    (State or other jurisdiction of                          (I.R.S.  Employer
      incorporation or organization                         Identification No.)

                            444 North Michigan Avenue
                             Chicago, Illinois 60611
               (Address, of Principal Executive Offices)(Zip Code)

                         The Second Amended and Restated
                     1995 Equity Incentive Plan of SPSS Inc.
                              (Full Title of Plan)

                                 Edward Hamburg
                       Executive Vice President, Corporate
                     Operations and Chief Financial Officer
                                    SPSS Inc.
                       233 South Wacker Drive, 11th Floor
                             Chicago, Illinois 60606
                     (Name and address of agent for service)
                                 (312) 651-3000
          (Telephone number, including area code, of agent for service)

                                   Copies To:
                          Lawrence R. Samuels, Esq.
                                 Ross & Hardies
                            150 North Michigan Avenue
                             Chicago, Illinois 60601
                                 (312) 558-1000

                         CALCULATION OF REGISTRATION FEE
====================================================================================================================
                                                      Proposed
       Title of              Amount to be             maximum             457 (h) Proposed          Amount of
     Securities to          Registered (1)         offering price            aggregate         Registration fee (2)
     be registered                                 per share (2)         offering price (2)
Common stock,                  1,119,750              $18.8125             $21,065,296.87           $6,214.26
$.01 par value
====================================================================================================================
2

(1)      The securities to be registered include a maximum of 1,119,750 shares
         issuable upon the exercise of options or as restricted shares under the
         Second Amended and Restated 1995 Equity Incentive Plan of SPSS Inc.
         assuming full participation of all employees under such plan.

(2)      Solely for purposes of calculating the registration fee, the offering
         price per share, the aggregate offering price and the amount of the
         registration fee have been computed in accordance with Rule 457(c)
         under the Securities Act of 1933, as amended. Accordingly, the price
         per share of Common Stock has been calculated to equal the average of
         the high and low prices of for a share of Common Stock, as reported on
         the Nasdaq National Market on September 3, 1998.

                                       2
3

PROSPECTUS

1,119,750 Shares
SPSS INC.

Common Stock
($.01 Par Value)

     This Prospectus relates to the offer and sale of up to 1,119,750 shares of
the common stock, $.01 par value (the "Common Shares" or "Common Stock"), of
SPSS Inc. (the "Company"). The Common Shares may be offered by particular
stockholders of the Company (the "Selling Stockholders") from time to time in
transactions on the Nasdaq National Market, in negotiated transactions, or a
combination of such methods of sale, at fixed prices that may be changed, at
market prices prevailing at the time of sale, at prices related to such
prevailing market prices or at negotiated prices. The Selling Stockholders may
effect such transactions by the sale of the Common Shares to or through
broker-dealers, and such broker-dealers may receive compensation in the form of
discounts, concessions or commissions from the Selling Stockholders and/or the
purchasers of the Common Shares for whom such broker-dealers may act as agent or
to whom they may sell as principal, or both (which compensation to a particular
broker-dealer might be in excess of customary commissions). The Selling
Stockholders and any broker-dealer who acts in connection with the sale of
Common Shares hereunder may be deemed to be "underwriters" as that term is
defined in the Securities Act of 1933, as amended (the "Securities Act"), and
any commission received by them and profit on any resale of the Common Shares as
principal might be deemed to be underwriting discounts and commissions under the
Securities Act. See "Selling Stockholders" elsewhere in this Prospectus. The
Company will not receive any of the proceeds from the sale of the Common Shares
by the Selling Stockholders.

     The Company's Common Stock is traded and quoted on the Nasdaq National
Market under the symbol "SPSS." On September 9, 1998, the last sale price of
the Common Stock, as reported on the Nasdaq National Market, was $19 per
share.

     The Company will bear all expenses (other than underwriting discounts and
selling commissions, and fees and expenses of counsel or other advisors to the
Selling Stockholders) in connection with the registration of the shares of
Common Stock being offered hereby.

See "Selling Stockholders" elsewhere in this Prospectus.

SEE "RISK FACTORS" ON BEGINNING PAGE 7 FOR A DISCUSSION OF CERTAIN FACTORS THAT
SHOULD BE CONSIDERED IN CONNECTION WITH AN INVESTMENT IN THE COMMON STOCK.

THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION, NOR HAS THE SECURITIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED UPON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.

               The date of this Prospectus is September 10, 1998

                                       3
4

                             AVAILABLE INFORMATION

     The Company is subject to the informational requirements of the Securities
Exchange Act of 1934, as amended (the "Exchange Act"), and in accordance
therewith files reports, proxy statements and other information with the
Securities and Exchange Commission (the "Commission"). Such reports, proxy
statements and other information filed by the Company, and the Registration
Statement of which this Prospectus forms a part, the exhibits and schedules
thereto and amendments thereof, may be inspected and copied at the public
reference facilities maintained by the Commission at 450 Fifth Street, N.W.,
Room 1024, Judiciary Plaza, Washington, D.C. 20549, and at the regional offices
of the Commission located at 7 World Trade Center, 13th Floor, New York, New
York 10048 and at Citicorp Center, 500 West Madison Street, Suite 1400, Chicago,
Illinois 60661-2511. Copies of such material can also be obtained from the
Public Reference Section of the Commission at 450 Fifth Street, N.W., Judiciary
Plaza, Washington, D.C. 20549 at prescribed rates. The Company's Common Stock is
quoted on the Nasdaq National Market, and therefore such reports, proxy
statements and other information can also be inspected at the offices of the
National Association of Securities Dealers, Inc., 1735 K Street, N.W., 3rd
Floor, Washington, D.C. 20006.

     Additional information regarding the Company and the shares offered hereby
is contained in the Registration Statement on Form S-8 and the exhibits thereto
(collectively, the "Registration Statement") filed with the Commission under the
Securities Act of 1933, as amended (the "Securities Act") in conjunction with
this Prospectus. As permitted by the rules and regulations of the Commission,
this Prospectus does not contain all of the information set forth in the
Registration Statement and the exhibits thereto, to which reference is hereby
made. Statements made in this Prospectus as to the contents of any contract,
agreement or other document referred to are not necessarily complete. With
respect to each such contract, agreement or other document filed as an exhibit
to the Registration Statement, reference is hereby made to the exhibit for a
more complete description of the matter involved, and each such statement will
be deemed qualified in its entirety by such reference. For further information
with respect to the Company and the shares of Common Stock offered hereby,
reference is hereby made to the Registration Statement, and the exhibits
thereto.

     SPSS, Categories, SYSTAT, Jandel Scientific, SigmaPlot, SigmaStat, Neural
Connection, Clear, Quancept, In2itive Technologies and In2Quest are registered
trademarks of the Company. SPSS/PC + SPSS Real Stats. Real Easy, QI Analyst,
BMDP, Jandel and Quantime are unregistered trademarks of the Company. allClear,
AnswerTree, TextSmart, SmartViewer and NewView are the subject of pending
applications for registration. This Prospectus also includes trade names and
marks of companies other than SPSS Inc.

                 INCORPORATION OF CERTAIN DOCUMENTS BY REFERENCE

     The Company hereby incorporates by reference the following documents
previously filed with the Commission:

                                       4
5

            (a) The Company's Annual Report on Form 10-K for the year ended 
     December 31, 1997;

            (b) The Company's Quarterly Report on Form 10-Q filed April 15, 1998
     for the fiscal quarter ended March 31, 1998.

            (c) The Company's Quarterly Report on Form 10-Q filed on August 14,
     1998 for the fiscal quarter ended June 30, 1998;

            (d) The description of the Company's Common Stock, $.01 par
     value (the "Common Stock"), contained in the Company's Registration
     Statement on Form 8-A filed with Commission on August 4, 1993, pursuant
     to Section 12 of the Exchange Act;

            (e) The description of the Company's Common Stock Purchase
     Rights, contained in the Company's Registration Statement on Form 8-A
     filed with the Commission on June 18, 1998; and

            (f) The Company's Proxy Statement, filed with the Commission
     on May 19, 1998, for its annual meeting of stockholders held on June
     17, 1998, except for the report of the Compensation Committee contained
     therein.

     All reports and other documents filed by the Company pursuant to Sections
13(a), 13(c), 14 and 15(d) of the Exchange Act, subsequent to the date of this
Prospectus and prior to the termination of the offering shall be deemed to be
incorporated by reference into the Prospectus and Registration Statement and to
be a part hereof from the date of filing of such documents. Any statement
contained herein or in a document incorporated or deemed to be incorporated by
reference herein shall be deemed to be modified or superseded for purposes of
this Prospectus to the extent that a statement contained herein, or in any
subsequently filed document which also is or is deemed to be incorporated by
reference herein, modifies or supersedes such statement. Any such statement so
modified or superseded shall not be deemed, except as so modified or superseded,
to constitute a part of this Prospectus.

     The Company will provide, without charge, to each person (including any
beneficial owner) to whom this Prospectus is delivered, upon written or oral
request of such person, a copy of any and all of the information that has been
incorporated by reference in this Prospectus (not including exhibits to such
information unless such exhibits are specifically incorporated by reference into
such information). Such requests should be directed to: Edward Hamburg,
Executive Vice President, Corporate Operations, Chief Financial Officer and
Secretary, at the Company's principal executive offices at 233 South Wacker
Drive, 11th Floor, Chicago, Illinois 60606, telephone (312) 651-3000.

                                       5
6

     UNLESS THE CONTEXT OTHERWISE REQUIRES, REFERENCES IN THIS PROSPECTUS TO
     "SPSS" AND THE "COMPANY" SHALL MEAN SPSS Inc. A DELAWARE CORPORATION, ITS
     ILLINOIS PREDECESSOR AND ITS SUBSIDIARIES, COLLECTIVELY; AND REFERENCES TO
     THE "COMMON STOCK" SHALL MEAN SPSS INC.'S COMMON STOCK, PAR VALUE $ .01 PER
     SHARE.

                                   THE COMPANY

GENERAL

     SPSS Inc. ("the Company") was incorporated in Illinois in 1975 under the
name "SPSS, Inc." and was reincorporated in Delaware in May 1993 under the name
"SPSS Inc." Unless the context otherwise requires, the terms "SPSS" and the
"Company" refer to SPSS Inc., a Delaware corporation, its Illinois predecessor
and its subsidiaries. SPSS is a multinational company that delivers reporting,
analysis and modeling software products, and whose primary markets are marketing
research, business analysis/data mining, scientific research and quality
improvement analysis. The Company develops, markets and supports an integrated
line of statistical software and other products that enable users to effectively
bring marketplace and enterprise data to bear on decision-making. The Company's
major products include SPSS for business and general applications, the Quantime
and In2itive family of products for market research, NewView for analytical
reporting, SigmaPlot and SYSTAT for scientific research, QI Analyst for quality
improvement and statistical process control, and allCLEAR for process
documentation and management. The primary users of the Company's software are
managers and data analysts in corporate settings, government agencies and
academic institutions. In addition to its widespread use in survey analysis,
SPSS software also performs other types of market research, as well as quality
improvement analyses, scientific and engineering applications and data
reporting. The current generation of SPSS Desktop products features a
windows-based point-and-click graphical user interface, sophisticated
statistical procedures, data access and management capabilities, report writing
and integrated graphics. The Company's products provide extensive analytical
capabilities not found in spreadsheets, database management systems or graphics
packages.

     In its 22 years as a corporation, SPSS has become a widely recognized name
in statistical software. The Company plans to leverage its current position to
take advantage of the increased demand for software applications that not only
provide ready access to the data that organizations collect and store, but also
enable users to systematically analyze, interpret and present such information
for use in decision-making. Management believes the ease-of-use of the Company's
current generation products, combined with the greater processing speed and
storage capacity of the latest desktop computers, has substantially expanded the
market for SPSS statistical software.

     In summer 1993, the Company completed an initial public offering (the
"IPO") of common stock, $.01 par value (the "Common Stock"). The Common Stock is
listed on the Nasdaq National Market under the symbol "SPSS". In early 1995, the
Company and certain selling stockholders (the "Selling Stockholders") sold
1,865,203 shares of Common Stock in a public offering.

                                       6
7

Safe Harbor

     "Safe Harbor" Statement under the Private Securities Litigation Reform Act
of 1995: With the exception of historical information, certain matters discussed
in this Prospectus are forward-looking statements, within the meaning of Section
21E of the Securities Exchange Act, as amended, that involve risks and
uncertainties including, but not limited to, market conditions, competition and
other risks indicated in this document, and the Company's other filings with the
Securities and Exchange Commission that could cause actual results to vary
materially from the future results indicated in such forward-looking statements.
No assurance can be given that the future results covered by the forward-looking
statements will be achieved. Other factors could also cause actual results to
vary materially from the future results indicated in such forward-looking
statements.

                                  RISK FACTORS

     Fluctuations in Quarterly Operating Results. The Company's quarterly
operating results can be subject to fluctuation due to several factors,
including the number and timing of product updates and new product
introductions, delays in product development and introduction, purchasing
schedules of its customers, changes in foreign currency exchange rates, product
and market development expenditures, the timing of product shipments, changes in
product mix, timing, costs and effects of acquisitions and general economic
conditions. Because the Company's expense levels are to a large extent based on
its forecasts of future revenues, operating results may be adversely affected if
such revenues fall below expectations. Accordingly, the Company believes that
quarter-to-quarter comparisons of its results of operations may not be
meaningful and should not be relied upon as an indication of future performance.
The Company has historically operated with very little backlog because its
products are generally shipped as orders are received. As a result, revenues in
any quarter are dependent on orders shipped and licenses renewed in that
quarter. The Company has experienced a seasonal pattern in its operating results
with the fourth quarter typically having the highest operating income. For
example, excluding acquisition and other non-recurring charges, the percentage
of the Company's operating income realized in the fourth quarter was, 33% in
1995, 32% in 1996 and 35% in 1997. In addition, the timing and amount of the
Company's revenues are subject to a number of factors that make estimation of
operating results prior to the end of a quarter uncertain. A significant portion
of the Company's operating expenses are relatively fixed, and planned
expenditures are based primarily on revenue forecasts. More specifically, in the
fourth quarter, the variable profit margins on modest increases in sales volume
at the end of the quarter are significant. Should the Company fail to achieve
such fourth quarter revenue increases, net income for the fourth quarter and the
full year could be materially affected. Generally, if revenues do not meet the
Company's expectations in any given quarter, operating results will be adversely
affected. There can be no assurance that profitability on a quarterly or annual
basis can be achieved or sustained in the future.

     Dependence on a Single Product Category; Declining Sales of Certain
Products. The Company derives the major part of its product revenues from
licenses of statistical software. Accordingly, any decline in revenues from
licenses of the Company's statistical software, or 

                                       7
8

reduction in demand for statistical software generally, could have a material
adverse effect on the Company.

     In recent years, SPSS, excluding the effects of the Quantime Limited and
In2itive Technologies A/S acquisitions, has experienced a significant shift in
the sources of its revenues. Historically, the Company derived a large portion
of its revenues from licenses of its mainframe and minicomputer ("Large
Systems") products. As a result of the general shift by computer users from
Large Systems to desktop computers, the Company experienced a decline in
revenues from Large Systems products in the last several years, although in 1996
sales of Large Systems products stabilized. Revenues from Large Systems licenses
declined from approximately $15.6 million in 1991 to $10.3 million in 1997,
while sales of desktop products increased from $14.7 million in 1991 to $81.3
million in 1997. Revenues from Large Systems licenses decreased from 1996 to
1997, by $400,000. Management is unable to predict whether the decline in Large
Systems licenses will continue or at what rate such licenses will decline.
Revenues from the Company's products for desktop computers ("Desktop products")
now account for nearly three-quarters of the Company's revenues and this
percentage may continue to increase.

     Risk Relating to Business Integration in Europe and Other Acquisitions. In
recent years, SPSS has made a significant number of acquisitions, including the
acquisition of businesses based outside of the United States. While SPSS has
substantial international operations, it faces challenges and business
integration issues with its September 1997 acquisition of Quantime and its
November 1997 acquisition of In2itive. Although persons whom the Company
believes are qualified and trained will continue to work with Quantime and
In2itive, there can be no assurance that Quantime or In2itive will be able to
retain these employees or hire suitable replacements in the event they should
leave the employ of SPSS. If the Company loses key personnel from Quantime or
In2itive or is unable to integrate Quantime's or In2itive's business into its
own effectively, the Company may experience a material adverse impact on its
financial condition. While SPSS believes that it has been successful in
integrating the acquisitions it has made in the past, there can be no assurance
that the recent acquisitions of Quantime or In2itive or future acquisitions will
be successfully integrated into SPSS.

     Rapid Technological Change. The computer software industry is characterized
by rapid technological advances, changes in customer requirements, frequent
product enhancements and new product introductions. The Company's future success
will depend upon its ability to enhance its existing products and introduce new
products that keep pace with technological developments, respond to evolving
customer requirements and achieve market acceptance. In particular, the Company
believes it must continue to respond quickly to users' needs for greater
functionality, improved usability and support for new hardware and operating
systems. Any failure by the Company to respond adequately to technological
developments and customer requirements, or any significant delays in product
development or introduction, could result in loss of revenues. In the past, the
Company has, on occasion, experienced delays in the introduction of new products
and product enhancements, primarily due to difficulties with particular
operating environments and problems with software provided by third parties. The
extent of these delays has varied depending upon the size and scope of the
project and the nature of the problems encountered. Such delays have most often
resulted from "bugs" encountered in working with new and/or beta-stage versions
of operating systems and other third party software, 

                                       8
9

and bugs or unexpected difficulties in existing third party software which
complicate integration with the Company's software. From time to time, the
Company has discovered bugs in its products which are resolved through
maintenance releases or through periodic updates depending upon the seriousness
of the defect. There can be no assurance that the Company will be successful in
developing and marketing new products or product enhancements on a timely basis
or that the Company will not experience significant delays or defects in its
products in the future, which could have a material adverse effect on the
Company. In addition, there can be no assurance that new products or product
enhancements developed by the Company will achieve market acceptance or that
developments by others will not render the Company's products or technologies
obsolete or noncompetitive.

     International Operations. The Company's revenues from operations outside of
North America accounted for approximately 52%, 53% and 50% of the Company's net
revenues in 1995, 1996 and 1997 respectively. The Company expects that revenues
from international operations will continue to represent a large percentage of
its net revenues and that this percentage may increase, particularly as the
Company further "localizes" the SPSS product line by translating its products
into additional languages and expands its operations through acquisitions of
companies outside the United States. International revenues are subject to a
number of risks, including greater difficulties in accounts receivable
collection, longer payment cycles, exposure to currency fluctuations, political
and economic instability and the burdens of complying with a wide variety of
foreign laws and regulatory requirements. The Company also believes that it is
exposed to greater levels of software piracy in international markets because of
the weaker protection afforded to intellectual property in some foreign
jurisdictions. As the Company expands its international operations, the risks
described above could increase and, in any event, could have a material adverse
effect on the Company.

     Potential Volatility of Stock Price. There has been significant
volatility in the market prices of securities of technology companies, including
SPSS, and, in some instances, such volatility has been unrelated to the
operating performance of such companies. Market fluctuations may adversely
affect the price of the Common Stock. The Company also believes factors such as
announcements of new products by the Company or its competitors, quarterly
variations in financial results, recommendations and reports of analysts,
acquisitions and factors beyond the Company's control could cause the market
price of the Common Stock to fluctuate substantially.

     Reliance on Relationships with Third Parties. The Company licenses certain
software from third parties. Some of this licensed software is embedded in the
Company=s products, and some is offered as add-on products. If such licenses are
discontinued, or become invalid or unenforceable, there can be no assurance that
the Company will be able to develop substitutes for this software independently
or to obtain alternative sources in a timely manner. Any delays in obtaining or
developing substitutes for licensed software could have a material adverse
effect on the Company.

     In April 1998, the Company entered into a new non-exclusive, worldwide
agreement (the "Prentice Hall Agreement") with Prentice Hall, Inc. ("Prentice
Hall") under which Prentice Hall publishes and distributes selected student
version software packages and Company publications. 

                                       9
10

As a result, the Company is dependent on Prentice Hall for the development and
support of the markets for student software and its publications. The failure of
Prentice Hall to perform its obligations under the Prentice Hall Agreement
adequately could have a material adverse effect on the Company. The Prentice
Hall Agreement has an initial term which expires in 2003, with an option to
renew for an additional five years under certain conditions.

     In January 1997, the Company entered into the Banta Global Turnkey Software
Distribution Agreement (the "Banta Agreement"), under which Banta Global Turnkey
("Banta") manufactures, packages, and distributes the Company's software
products to the Company's domestic and international customers and certain
international subsidiaries. The Banta Agreement has a three-year term and
automatically renews thereafter for successive periods of one year. Either party
may terminate the Banta Agreement for cause by written notice if the other
materially breaches its obligations. Such a termination notice for cause must
specifically identify the breach (or breaches) upon which it is based and will
be effective 180 days after the notice is received by the other party, unless
the breach(es) is (are) corrected during the 180 days. Either party may also
terminate the Banta Agreement on 180 days' notice for any other reason. If Banta
terminates the Banta Agreement other than for cause, it is required to assist
the Company in finding a new vendor. If Banta fails to perform adequately any of
its obligations under the Banta Agreement, the Company's operating results could
be materially adversely affected.

     Changes in Public Expenditures and Overall Economic Activity Levels. A
significant portion of the Company's revenues comes from licenses of its
products directly to foreign and domestic government entities. In addition,
significant amounts of the Company's revenues come from licenses to academic
institutions, Healthcare organizations and private businesses which contract
with or are funded by government entities. Government appropriations processes
are often slow, unpredictable and subject to factors outside the Company's
control. In addition, proposals are currently being made in certain countries to
reduce government spending. Reductions in government expenditures and
termination or renegotiation of government-funded programs or contracts could
have a material adverse effect on the Company. In addition, declines in overall
levels of economic activity could also have a material adverse impact on the
Company.

     Competition. The market for the statistical software is both highly
competitive and fragmented. The Company primarily competes with one general
statistical software provider which is larger and has greater resources than the
Company, as well as with numerous other companies offering statistical
applications software, many of which offer products focused on specific
statistical applications. The Company considers its primary worldwide competitor
to be the larger and better-financed SAS Institute ("SAS"), although the Company
believes that SAS's revenues are derived principally from products that are used
for purposes other than statistics and operate on large systems platforms.
StatSoft Inc., developers of the Statistica product ("Statistica"), Manugistics
Group, Inc., distributors of the Statgraphics Plus product ("Statgraphics"), and
Minitab, Inc. ("Minitab") are also competitors, although their annual revenues
from statistical products are believed to be considerably less than the revenues
of SPSS.

                                       10
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     In the future, SPSS may face competition from new entrants into the
statistical software market. The Company could also experience competition from
companies in other sectors of the broader market for data management, analysis
and presentation software, such as providers of spreadsheets, database
management systems, report writers and executive information systems. These
companies have added, or in the future may add, statistical analysis
capabilities to their products. Many of these companies have significant name
recognition, as well as substantially greater capital resources, marketing
experience and research and development capabilities than the Company. There can
be no assurance that the Company will have sufficient resources to make the
necessary investment in research and development and sales and marketing, or
that the Company will otherwise be able to make the technological advances
necessary to maintain or enhance its competitive position. The Company's future
success will also depend significantly upon its ability to continue to sell its
Desktop products, to attract new customers looking for more sophisticated or
powerful software and to introduce additional add-on products to existing
customers. There can be no assurance that the Company will be able to compete
successfully in the future.

     Dependence on Key Personnel. The Company is dependent on the efforts of
certain executives and key employees, including its President and Chief
Executive Officer, Jack Noonan. The Company's continued success will depend in
part on its ability to attract and retain highly qualified technical,
managerial, sales, marketing and other personnel. Competition for such personnel
is intense. There can be no assurance that the Company will be able to continue
to attract or retain such highly qualified personnel. No life insurance policies
are maintained on the Company's key personnel.

     Intellectual Property; Proprietary Rights. The statistical algorithms
incorporated in the Company's software are not proprietary. The Company believes
that the proprietary technology constituting a portion of the Company's software
determines the speed and quality of displaying the results of computations, the
connectivity of the Company's products with third party software and the ease of
use of its products. The Company's success will depend, in part, on its ability
to protect the proprietary aspects of its products. The Company attempts to
protect its proprietary software with trade secret laws and internal
nondisclosure safeguards, as well as copyright and trademark laws and
contractual restrictions on copying, disclosure and transferability that are
incorporated into its software license agreements. The Company licenses its
software only in the form of executable code, with contractual restrictions on
copying, disclosures and transferability. Except for licenses of its products to
users of Large System products and annual licenses of its Desktop products, the
Company licenses its products to end-users by use of a "shrink-wrap" license
that is not signed by licensees, as is customary in the industry. It is
uncertain whether such license agreements are legally enforceable. The source
code for all of the Company's products is protected as a trade secret and as
unpublished copyrighted work. In addition, the Company has entered into
confidentiality and nondisclosure agreements with its key employees. Despite
these restrictions, it may be possible for competitors or users to copy aspects
of the Company's products or to obtain information which the Company regards as
a trade secret. The Company has no patents, and judicial enforcement of
copyright laws may be uncertain, particularly outside of North America.
Preventing unauthorized use of computer software is difficult, and software
piracy is expected to be a persistent problem for the packaged software
industry. These problems may be particularly acute in international markets. In
addition, the 

                                       11
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laws of certain countries in which the Company's products are or may be licensed
do not protect the Company's products and intellectual property rights to the
same extent as the laws of the United States. Despite the precautions taken by
the Company, it may be possible for unauthorized third parties to reverse
engineer or copy the Company's products or obtain and use information that the
Company regards as proprietary. There can be no assurance that the steps taken
by the Company to protect its proprietary rights will be adequate to prevent
misappropriation of its technology.

     Although the Company's products have never been the subject of an
infringement claim, there can be no assurance that third parties will not assert
infringement claims against the Company in the future or that any such assertion
will not result in costly litigation or require the Company to obtain a license
to use the intellectual property of third parties. There can be no assurance
that such licenses will be available on reasonable terms, or at all. There can
also be no assurance that the Company's competitors will not independently
develop technologies that are substantially equivalent or superior to the
Company's technologies.

     Control by Existing Stockholders; Antitakeover Effects. As of August 10,
1998, the Company's executive officers and directors owned beneficially
approximately 21.5% of the outstanding shares of Common Stock. The Norman H. Nie
Revocable Trust Dated March 15, 1991 (the "Nie Trust") and affiliates of the Nie
Trust are entitled to nominate a director for inclusion in the management slate
for election to the Board if the Nie Trust owns no less than 12.5% of the
outstanding shares of Common Stock. As of August 10, 1998, the Nie Trust and
affiliates of the Nie Trust beneficially owned approximately 12.6% of the
outstanding shares of Common Stock. The Company's Certificate of Incorporation
and Bylaws contain a number of provisions, including provisions requiring an 80%
super majority stockholder approval of certain actions and provisions for a
classified Board of Directors, which would make the acquisition of the Company,
by means of an unsolicited tender offer, a proxy contest or otherwise, more
difficult or impossible.

     In June 1998, the Company adopted a Rights Agreement. The Board declared a
distribution of one Right for each share of Common Stock then outstanding. Each
share of Common Stock has an attached Right. The Rights are not exercisable or
detachable from the Common Stock. The Rights will become exercisable and
detachable only following the acquisition by a person or a group of 15 percent
or more of the outstanding Common Stock or following the announcement of a
tender or exchange offer for 15 percent or more of the outstanding Common Stock.

     The Rights will, if they become exercisable, permit the holders of the
Rights to purchase one share of Common Stock of the Company, or to exchange the
Rights for cash, property or other securities, if the Board permits. Where an
acquiring company effects a merger or other control transaction with the
Company, the Rights may also entitle the holder to acquire stock of the
acquiring company at 50 percent of its value. If a person or group acquires 15
percent or more of the Common Stock (or announces a tender or exchange offer for
15 percent or more of the Common Stock), the acquiring person=s or group=s
Rights become void. In certain circumstances, the Rights may be redeemed by the
Company at an initial redemption price of $.01 per Right.

                                       12
13

     Shares Eligible for Future Sale. The Company has filed a Registration
Statement to permit transactions with respect to the shares of Common Stock
issued in connection with the Quantime and In2itive transactions.

     In addition to the shares of Common Stock which are outstanding, as of
August 10, 1998, there were vested options outstanding held by the executive
officers and directors to purchase and beneficially own approximately an
additional 798,373 shares of Common Stock, with an average exercise price of
$12.94 per share, and unvested options to purchase approximately an additional
210,637 shares of Common Stock. The Company has also established a stock
purchase plan available to employees of the Company, which permits employees to
acquire shares of Common Stock at the end of each quarter at 85% of the market
price of the Common Stock as of the day after the end of the quarter.

     No prediction can be made as to the effect, if any, that future sales, or
the availability of shares of Common Stock for future sales, will have on the
market price prevailing from time to time. Sales of substantial amounts of
Common Stock by the Company or by shareholders or the perception that such sales
may occur, could adversely affect prevailing market prices for the Common Stock.

     Year 2000. Many computer systems and applications currently use two digits
to define the applicable year. As a result, date-sensitive systems may recognize
the year 2000 as 1900 or not at all, which could cause miscalculations or system
failures. The Company has not completed its assessment of its computerized
systems to determine their ability to correctly identify the year 2000, but
currently believes that costs of addressing this issue will not have a material
adverse impact on the Company=s financial position. However, if the Company and
third parties upon which it relies are unable to address this issue in a timely
manner, it could result in a material financial risk to the Company. In order to
assure that this does not occur, the Company plans to devote all resources
required to resolve any significant year 2000 issues in a timely manner.

     Accumulated Deficit. The Company had an accumulated deficit of $4,797,000
as of June 30, 1998.

                                       13
14

                              SELLING STOCKHOLDERS

     The following table sets forth the number of shares of Common Stock
beneficially owned by each Selling Stockholder as of August 10, 1998 the number
of shares of Common Stock that may be offered for the Selling Stockholder's
account and based on the number of shares of Common Stock beneficially owned as
of August 10, 1998 the percentage of the shares of Common Stock to be
beneficially owned by such Selling Stockholder if they elect to sell all of
their Shares of Common Stock that are available for sale.
Shares of Common
                                            Shares of                                       Stock To Be
                                           Common Stock          Maximum Number of       Beneficially Owned
                                        Beneficially Owned       Shares Available        Assuming Sale of All
               Name of                         As of                To Be Sold           Shares Available For
         Selling Stockholder              August 10, 1998         Pursuant Hereto         Sale Hereunder (1)
         -------------------              ---------------         ---------------         ------------------
 
                                                                                          Number      Percent
                                                                                          ------      -------
Jack Noonan (2)                                229,674                 50,000              179,674       1.9%

Edward Hamburg (3)                             131,357                 25,000              106,357       1.2%

Louise E.  Rehling (4)                         102,355                 25,000               77,355        *

Susan Phelan (5)                                95,907                 25,000               70,907        *

Mark Battaglia (6)                             105,340                 25,000               80,340        *

Ian Durell (7)                                  50,624                 25,000               25,624        *

Norman Nie (8)                               1,140,448                 10,000            1,130,448      12.4%

Merritt Lutz (9)                                28,204                 10,000               18,204        *

Bernard Goldstein (10)                          44,315                 10,000               34,315        *

Fredric Harman (11)                              8,919                 10,000                 --          *

Michael Blair (12)                               2,918                 10,000                 --          *
*    The percentage of shares beneficially owned does not exceed 1% of the 
     class.

(1)  Based upon the number of Shares of Common Stock outstanding on August
     10, 1998. Assumes all stock that may be offered pursuant to this Prospectus
     is sold, and no other shares beneficially owned by the Selling Stockholders
     are sold.

(2)  Includes 221,508 shares subject to options exercisable within 60 days.  
     Mr. Noonan is President, Chief Executive Officer and Director of the 
     Company.

                                       14
15

(3)  Includes 121,357 shares subject to options exercisable within 60 days. 
     Mr. Hamburg is Executive Vice President, Corporate Operations, Chief
     Financial Officer and Secretary of the Company.

(4)  Includes 98,290 shares subject to options exercisable within 60 days.
     Includes 200 shares held in the Stella S. Hechtman Trust (the ATrust@). Ms.
     Rehling is the Trustee and has the voting and investment power over the 200
     shares held in the Trust. She disclaims beneficial ownership of these
     shares. Ms. Rehling is Executive Vice President, Product Development of the
     Company.

(5)  Includes 93,921 shares subject to options exercisable within 60 days.
     Ms. Phelan is Executive Vice President, Domestic Sales and Services of the
     Company. Previously, Ms. Phelan was Executive Vice President SPSS Products
     and Services.

(6)  Includes 104,957 shares subject to options exercisable within 60 days.  
     Mr. Battaglia is Executive Vice President, Corporate Marketing of the
     Company.

(7)  Mr. Durrell is the beneficial owner of these shares which consist solely 
     of 50,624 shares subject to options exercisable within 60 days held of
     record by Valletta Investments. Mr. Durrell is Executive Vice President,
     SPSS Market Research. Previously Mr. Durrell was Executive Vice President,
     International of the Company.

(8)  Includes 78,815 shares subject to options exercisable within 60 days;
     110,433 shares held of record by the Norman and Carol Nie Foundation, Inc.
     (the "Nie Foundation"); and 951,200 shares held by the Nie Trust. Professor
     Nie shares voting and investment power over the 110,433 shares held by the
     Nie Foundation with Carol Nie. Dr. Nie is Chairman of the Board of the
     Company.

(9)  Includes 8,871 shares subject to options exercisable within 60 days.
     Mr. Lutz is a Director of the Company. Mr. Lutz shares voting power over 
     6,000 of these shares with Mary C. Lutz.

(10) Includes 8,871 shares subject to options exercisable within 60 days.  
     Mr. Goldstein is a Director of the Company.

(11) Includes 8,871 shares subject to options exercisable within 60 days.  
     Mr. Harman is a Director of the Company.

(12) Includes 2,918 shares subject to options exercisable within 60 days.  
     Mr. Blair is a Director of the Company.

                                 USE OF PROCEEDS

     The Company will not receive any proceeds from the registration or sale of
the shares of Common Stock offered hereby.

                                       15
16

                        DIVIDEND POLICY AND RESTRICTIONS

     The Company has never declared any cash dividends or distributions on its
capital stock and does not anticipate paying cash dividends in the foreseeable
future. The Company currently intends to retain its future earnings to fund
ongoing operations and future capital requirements of its business.

                              PLAN OF DISTRIBUTION

     The Common Stock may be offered by the Selling Stockholders from time to
time in transactions on the Nasdaq National Market, in negotiated transactions,
or a combination of such methods of sale, at fixed prices that may be changed,
at market prices prevailing at the time of sale, at prices related to such
prevailing market prices or at negotiated prices. The Selling Stockholders may
effect such transactions by the sale of the Common Stock to or through
broker-dealers, and such broker-dealers may receive compensation in the form of
discounts, concessions or commissions from the selling Stockholders and/or the
purchasers of the Common Stock for whom such broker-dealers may act as agent or
to whom they may sell as principal, or both (which compensation to a particular
broker-dealer might be in excess of customary commissions). The Selling
Stockholders and any broker-dealer who acts in connection with the sale of
Common Stock hereunder may be deemed to be "underwriters" as that term is
defined in the Securities Act, and any commission received by them and profit on
any resale of the Common Stock as principal might be deemed to be underwriting
discounts and commissions under the Securities Act.

     No prediction can be made as to the effect, if any, that future sales, or
the availability of shares of Common Stock for future sales, will have on the
market price prevailing from time to time. See "RISK FACTORS -- Shares Eligible
for Future Sale" elsewhere in this Prospectus.

                                  LEGAL MATTERS

     The validity of the shares of Common Stock is being passed upon for the
Company by Ross & Hardies, Chicago, Illinois.

                                     EXPERTS

     The consolidated financial statements of SPSS Inc. and subsidiaries as of
December 31, 1997 and 1996 and for each of the three years in the period ended
December 31, 1997, have been incorporated by reference herein from the Companys
Annual Report on Form 10-K for the year ended December 31, 1997 in reliance upon
the report of KPMG Peat Marwick LLP, independent certified public accountants,
incorporated by reference herein, and upon the authority of said firm in
accounting and auditing.

     With respect to the unaudited interim financial information for the periods
ended March 31, 1998 and 1997, and June 30, 1998 and 1997, incorporated by
reference herein, the independent certified public accountants have reported
that they applied limited procedures in accordance with professional standards
for a review of such information. However, their
17

                                   

separate reports included in the Company's quarterly reports on Form 10-Q for
the quarters ended March 31, 1998 and June 30, 1998, and incorporated by
reference herein, states that they did not audit and they do not express an
opinion on that interim financial information. Accordingly, the degree of
reliance on their report on such information should be restricted in light of
the limited nature of the review procedures applied. The accountants are not
subject to the liability provisions of section 11 of the Securities Act of 1933
for their report on the unaudited interim financial information because that
report is not a Areport@ or a Apart@ of the registration statement prepared or
certified by the accountants within the meaning of sections 7 and 11 of the Act.

                                       17
18

NO DEALER, SALESMAN OR OTHER PERSON HAS BEEN AUTHORIZED TO GIVE ANY INFORMATION
OR TO MAKE ANY REPRESENTATIONS OTHER THAN THOSE CONTAINED IN THIS PROSPECTUS IN
CONNECTION WITH THE OFFER MADE BY THIS PROSPECTUS AND, IF GIVEN OR MADE, SUCH
INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED
BY THE COMPANY. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR ANY SALE MADE
HEREUNDER SHALL UNDER ANY CIRCUMSTANCES CREATE AN IMPLICATION THAT THERE HAS
BEEN NO CHANGE IN THE AFFAIRS OF THE COMPANY SINCE THE DATE HEREOF. THIS
PROSPECTUS DOES NOT CONSTITUTE AN OFFER OR SOLICITATION BY ANYONE IN ANY
JURISDICTION IN WHICH SUCH OFFER OR SOLICITATION IS NOT AUTHORIZED OR IN WHICH
THE PERSON MAKING SUCH OFFER OR SOLICITATION IS NOT AUTHORIZED OR IN WHICH THE
PERSON MAKING SUCH OFFER OR TABLE OF CONTENTS SOLICITATION IS NOT QUALIFIED TO
DO SO OR TO ANYONE TO WHOM IT IS UNLAWFUL TO MAKE SUCH OFFER OR SOLICITATION.

                                TABLE OF CONTENTS
Page
Available Information....................................................... 4
Incorporation of Certain Documents by Reference............................. 4
The Company................................................................. 6
Risk Factors................................................................ 7
Selling Stockholders........................................................15
Use of Proceeds.............................................................16
Dividend Policy and Restrictions............................................17
Plan of Distribution........................................................17
Legal Matters...............................................................17
Experts.....................................................................17
1,119,750 Shares

SPSS INC.

COMMON STOCK
($.01 PAR VALUE)

Prospectus

Dated September 10, 1998

                                       18
19

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3.  Incorporation of Certain Documents by Reference

     SPSS Inc. (the "Company") hereby incorporates by reference the
following documents previously filed with the Securities and Exchange Commission
(the "Commission"):

         (a)      The Company's Annual Report on Form 10-K for the year ended 
     December 31, 1997;

         (b)      The Company's Quarterly Report on Form 10-Q filed April 15, 
     1998 for the fiscal quarter ended March 31, 1998;

         (c)      The Company's Quarterly Report on Form 10-Q filed on August
     14, 1998 for the fiscal quarter June 30, 1998;

         (d)      The description of the Company's Common Stock, $.01 par value
     (the "Common Stock"), contained in the Company's Registration Statement on 
     Form 8-A filed with Commission on August 4, 1993, pursuant to Section 12 
     of the Exchange Act;

         (e)      The description of the Company's Common Stock Purchase Rights,
     contained in the Company's Registration Statement on Form 8-A filed with 
     the Commission on June 18, 1998; and

         (f)      The Company's Proxy Statement, filed with the Commission on 
     May 19, 1998, for its annual meeting of stockholders held on June 17, 1998,
     except for the report of the Compensation Committee contained therein.

     All documents subsequently filed by the Company pursuant to Sections 13(a),
13(c), 14 and 15(d) of the Exchange Act, subsequent to the effective date of the
Registration Statement and prior to filing of a post-effective amendment to the
Registration Statement which indicates that all securities offered have been
sold or which deregisters all securities then remaining unsold, shall be deemed
incorporated by reference in the Registration Statement and to be a part hereof
from the date of filing of such documents.

Item 4.  Description of Securities

         Not applicable.

Item 5.  Interests of Named Experts and Counsel

         Not applicable.

Item 6.  Indemnification of Officers and Directors

                                       19
20

     Delaware General Corporation Law. The Company has statutory authority to
indemnify its officers and directors. The applicable provisions of the General
Corporation Law of the State of Delaware (the "GCL") state that, to the extent
such person is successful on the merits or otherwise, a corporation may
indemnify any person who was or is a party or who is threatened to be made a
party to any threatened, pending or completed action, suit or proceeding,
whether civil, criminal, administrative or investigative (other than an action
by or in the right of the corporation), by reason of the fact that he is or was
a director, officer, employee or agent of the corporation or is or was serving
at the request of the corporation as a director, officer, employee or agent of
another corporation, partnership, joint venture, trust or other enterprise
("such Person"), against expenses (including attorneys' fees), judgments, fines
and amounts paid in settlement, actually and reasonably incurred by such Person,
if he acted in good faith and in a manner he reasonably believed to be in or not
opposed to the best interests of the corporation and with respect to any
criminal action or proceeding, had no reasonable cause to believe his conduct
was unlawful. In any threatened pending or completed action by or in the right
of the corporation, a corporation also may indemnify any such Person for costs
actually and reasonably incurred by him in connection with that action's defense
or settlement, if he acted in good faith and in a manner he reasonably believed
to be in or not opposed to the best interests of the corporation; however, no
indemnification shall be made with respect to any claim, issue or matter as to
which such Person shall have been adjudged to be liable to the corporation,
unless and only to the extent that a court shall determine that such indemnity
is proper.

Under the applicable provisions of the GCL, any indemnification shall be made by
the corporation only as authorized in the specific case upon a determination
that the indemnification of the director, officer, employee or agent is proper
in the circumstances because he has met the applicable standard of conduct. Such
determination shall be made:

     (1) By the Board of Directors by a majority vote of a quorum consisting of
         directors who are not parties to such action, suit or proceeding; or

     (2) If such a quorum is not obtainable or, even if obtainable, a quorum of
         disinterested directors so directs, by independent legal counsel in a 
         written opinion; or

     (3) By the affirmative vote of a majority of the shares entitled to
         vote thereon.

The Company's Certificate of Incorporation provides for indemnification to the
full extent permitted by the laws of the State of Delaware against and with
respect to threatened, pending or completed actions, suits or proceedings
arising from or alleged to arise from, a party's actions or omissions as a
director, officer, employee or agent of the Company or of any subsidiary of the
Company or of any other corporation, partnership, joint venture, trust or other
enterprise which he has served in such capacity at the request of the Company if
such acts or omissions occurred or were or are alleged to have occurred, while
said party was a director or officer of the Company.

     The Company maintains a director and officer liability insurance policy
which indemnifies directors and officers for certain losses arising from a claim
by reason of a wrongful 

                                       20
21

act, as defined, under certain circumstances where the Company does not provide
indemnification.

Item 7.  Exemption from Registration Claimed.

         Not applicable.

Item 8.  Exhibits.
Incorporation
                                                                       by
Exhibit                                                            Reference
Number   Description of Document                                 (if applicable)
4.1      Loan Agreement                                                 *

5.1      Opinion of Ross & Hardies regarding legality of shares 
         of Common Stock

15.1     Letter re: Unaudited Interim Financial Information

23.1     Consent of KPMG Peat Marwick LLP

23.2     Consent of Ross & Hardies

24.1     Power of Attorney                                             ***
*        Previously filed with SPSS' Form 10-Q for the Quarterly Period Ended 
         on June 30, 1998 
***      Included in signature pages.

 (b)     The Company did not file any reports on Form 8-K during fiscal year

Item 9.  Undertakings.

         (a)      The undersigned Registrant hereby undertakes:

                  (1)      To file, during any period in which offers or sales 
                           are being made, a post-effective amendment to this 
                           Registration Statement:

                           (i)     To include any prospectus required by 
                                   Section 10(a)(3) of the Securities Act of 
                                   1933;

                           (ii)    To reflect in the prospectus any facts or 
                                   events arising after the effective date of
                                   this Registration Statement (or the most
                                   recent post-effective amendment thereof)
                                   which, individually or in the aggregate,
                                   represent a fundamental change in the
                                   information set forth in this Registration
                                   Statement. Notwithstanding the foregoing, any
                                   increase or
                                            

                                       21
22

                                  decrease in volume of securities offered (if
                                  the total dollar value of securities offered
                                  would not exceed that which was registered)
                                  and any deviation from the low or high end of
                                  the estimated maximum offering range may be
                                  reflected in the form of prospectus filed with
                                  the Commission pursuant to Rule 424(b) if, in
                                  the aggregate, the changes in volume and price
                                  represent no more than a 20% change in the
                                  maximum aggregate offering price set forth in
                                  the "Calculation of Registration Fee" table in
                                  the effective Registration Statement.

                          (iii)   To include any material information with 
                                  respect to the plan of distribution not
                                  previously disclosed in this Registration
                                  Statement or any material change to such
                                  information in this Registration Statement;

                          provided, however, that paragraphs (a)(1)(i) and
                          (a)(1)(ii) do not apply if the registration statement
                          is on Form S-3, Form S-8 or Form F-3, and the
                          information required to be included in a
                          post-effective amendment by those paragraphs is
                          contained in periodic reports filed by the Registrant
                          pursuant to Section 13 or Section 15(d) of the
                          Securities Exchange Act of 1934 that are incorporated
                          by reference in this Registration Statement.

                 (2)      That, for the purpose of determining any liability 
                          under the Securities Act of 1933, each such
                          post-effective amendment shall be deemed to be a new
                          registration statement relating to the securities
                          offered therein, and the offering of such securities
                          at that time shall be deemed to be the initial bona
                          fide offering thereof.

                 (3)      To remove from registration by means of a 
                          post-effective amendment any of the securities being
                          registered which remain unsold at the termination of
                          the offering.

        (b)      The undersigned Registrant hereby undertakes that for purposes 
                 of determining any liability under the Securities Act of 1933,
                 each filing of the Registrant's annual report pursuant to
                 Section 13(a) or Section 15(d) of the Securities Exchange Act
                 of 1934 (and, where applicable, each filing of an employee
                 benefit plan's annual report pursuant to Section 15(d) of the
                 Securities Exchange Act of 1934) that is incorporated by
                 reference in this Registration Statement shall be deemed to be
                 a new registration statement relating to the securities offered
                 herein and the offering of such securities at that time shall
                 be deemed to be the initial bona fide offering thereof.

        (c)      The undersigned Registrant hereby undertakes that, insofar as 
                 indemnification for liabilities arising under the Securities 
                 Act of 1933 may 

                                       22
23

         be permitted to directors, officers and controlling persons of the
         registrant pursuant to the foregoing provisions, or otherwise, the
         registrant has been advised that in the opinion of the Securities and
         Exchange Commission such indemnification is against public policy as
         expressed in the Act and is, therefore, unenforceable.  In the event
         that a claim for indemnification against such liabilities (other than
         the payment by the registrant of expenses incurred or paid by a
         director, officer or controlling person of the registrant in the
         successful defense of any action, suit or proceeding) is asserted by
         such director, officer or controlling person in connection with the
         securities being registered, the registrant will, unless in the opinion
         of its counsel the matter has been settled by controlling precedent,
         submit to a court of appropriate jurisdiction the question of whether
         such indemnification by it is against public policy as expressed in the
         Act and will be governed by the final adjudication of such issue.

                                       23
24

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Chicago, State of Illinois, on September 10, 1998.

                                     SPSS INC.

                                     By: /s/ Jack Noonan 
                                         -------------------------------------  
                                         Jack Noonan
                                         President and Chief Executive Officer

                                POWER OF ATTORNEY

     Each person whose signature appears below hereby constitutes and appoints
Jack Noonan and Edward Hamburg, and each of them, the true and lawful
attorneys-in-fact and agents of the undersigned, with full power of substitution
and resubstitution, for and in the name, place and stead of the undersigned, in
any and all capacities, to sign any and all amendments (including post-effective
amendments) to this Registration Statement, and to file the same, with all
exhibits thereto, and other documents in connection therewith, with the
Securities and Exchange Commission, and hereby grants to such attorneys-in-fact
and agents, and each of them, full power and authority to do and perform each
and every act and thing requisite and necessary to be done in furtherance of the
foregoing, as fully to all intents and purposes as the undersigned might or
could do in person, hereby ratifying and confirming all that said
attorneys-in-fact and agents, or any of them, or their or his substitute or
substitutes, may lawfully do or cause to be done by virtue hereof.

     Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities indicated on September 10, 1998.

Signature                      Title(s)

/s/ Norman H. Nie              Chairman of the Board
-----------------------
Norman H.  Nie

/s/ Jack Noonan                President, Chief Executive Officer
-----------------------        and Director
Jack Noonan                         

/s/ Edward Hamburg             Executive Vice President, Corporate Operations,
-----------------------        Chief Financial Officer and Secretary
Edward Hamburg                 

/s/ Robert Brinkmann           Controller and Assistant Secretary
-----------------------        (Chief Accounting Officer)
Robert Brinkmann        

                                       24
25

/s/ Bernard Goldstein                       Director
-------------------------
Bernard Goldstein

/s/ Fredric W. Harman                       Director
-------------------------
Fredric W. Harman

/s/ Merritt Lutz                            Director
-------------------------
Merritt Lutz

/s/ Michael Blair                           Director
-------------------------
Michael Blair

                                       25
26

                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                               EXHIBITS FILED WITH

                 THE POST EFFECTIVE AMENDMENT NO. 1 ON FORM S-8

                             REGISTRATION STATEMENT

                                      UNDER

                           THE SECURITIES ACT OF 1933

                                    SPSS INC.
27

                                   SPSS INC.

                                                                    Location of
                                                                    Document in
                                                                    Sequential
                                                                     Numbering
Exhibit No.       Description                                         System 

    5.1           Opinion of Ross & Hardies regarding legality of 
                  shares of Common Stock
                 

   15.1           Letter re: Unaudited Interim Financial Information.

   23.1           Consent of KPMG Peat Marwick LLP

   23.2           Consent of Ross & Hardies (contained in opinion filed as 
                  Exhibit 5.1)

   24.1           Power of Attorney (contained in signature pages)