<PAGE>   1
    AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JANUARY 20, 1998


                                                           Registration No. 333-


                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-8

                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933


                             ASPEN TECHNOLOGY, INC.
             (Exact Name of Registrant as Specified in Its Charter)

     MASSACHUSETTS                                 04-2739697
(State or Other Jurisdiction of                   (I.R.S. Employer
Incorporation or Organization)                     Identification No.)

                 TEN CANAL PARK, CAMBRIDGE, MASSACHUSETTS 02141
               (Address of Principal Executive Offices) (Zip Code)


            ASPEN TECHNOLOGY, INC. 1998 EMPLOYEE STOCK PURCHASE PLAN
                            (Full Title of the Plan)

                                LAWRENCE B. EVANS
                     Chairman of the Board of Directors and
                            Chief Executive Officer
                             ASPEN TECHNOLOGY, INC.
                                 Ten Canal Park
                         Cambridge, Massachusetts 02141
                     (Name and Address of Agent for Service)

                                 (617) 949-1000
          (Telephone Number, Including Area Code, of Agent for Service)

                                 With copies to:

       STEPHEN J. DOYLE, ESQ.                       MARK L. JOHNSON, ESQ.
 Vice President and General Counsel               FOLEY, HOAG & ELIOT LLP
       ASPEN TECHNOLOGY, INC.                      One Post Office Square
           Ten Canal Park                       Boston, Massachusetts 02109
   Cambridge, Massachusetts 02141                      (617) 832-1000
           (617) 949-1000



<TABLE>
<CAPTION>
                         CALCULATION OF REGISTRATION FEE
===================================================================================================================
               Title of                     Amount             Proposed               Proposed         Amount of
           Securities to be                 to be          Maximum Offering       Maximum Aggregate   Registration
              Registered                  Registered     Price Per Share(2)(3)    Offering Price(2)       Fee
-------------------------------------------------------------------------------------------------------------------
<S>                                    <C>                      <C>                  <C>                 <C>
Common Stock, $.10 par value(1)        1,000,000 shares         $30.25               $30,250,000         $7,586
===================================================================================================================
</TABLE>

(1)      Each share of Common Stock will be accompanied by one Right to purchase
         Series A Participating Cumulative Preferred Stock of the Registrant.
(2)      Estimated solely for the purpose of determining the registration fee. 
(3)      In accordance with Rules 457(c) and (h) under the Securities Act of
         1933, the calculation is based on 85% of the average of the high and
         low sale prices reported in the consolidated reporting system of the
         Nasdaq National Market on January 12, 1998.
<PAGE>   2
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.    INCORPORATION OF DOCUMENTS BY REFERENCE.

           The following documents heretofore filed by Aspen Technology, Inc.
(the "Company") with the Securities and Exchange Commission (the "Commission")
pursuant to the Securities Exchange Act of 1934, as amended (the "Exchange Act")
are incorporated herein by reference:

           (1)    the Company's Annual Report on Form 10-K for the fiscal year
                  ended June 30, 1997, filed on September 29, 1997 pursuant to
                  Section 12 of Exchange Act;

           (2)    the Company's Quarterly Report on Form 10-Q for the quarterly
                  period ended September 30, 1997, filed on November 14, 1997
                  pursuant to Section 13 of the Exchange Act;

           (3)    the Company's Current Report on Form 8-K dated October 9,
                  1997, filed on October 10, 1997 pursuant to Section 13 of the
                  Exchange Act;

           (4)    the Company's definitive Proxy Statement dated October 29,
                  1997, filed on December 1, 1997 pursuant to Section 14 of
                  the Exchange Act; 

           (5)    the description of the Company's Common Stock contained in the
                  Registration Statement on Form 8-A filed on September 6, 1996
                  under Section 12 of the Exchange Act; and

           (6)    the description of the Company's Rights to purchase Series A
                  Participating Cumulative Preferred Stock contained in the
                  Registration Statement on Form 8-A filed on October 10, 1997
                  under Section 12 of the Exchange Act.

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


ITEM 4.    DESCRIPTION OF SECURITIES.

           Not applicable.


ITEM 5.    INTERESTS OF NAMED EXPERTS AND COUNSEL.

           Not applicable.


                                      II-1
<PAGE>   3
ITEM 6.    INDEMNIFICATION OF DIRECTORS AND OFFICERS.

           Section 67 of Chapter 156B of the Massachusetts General Laws provides
a statutory framework covering indemnification of directors and officers against
liabilities and expenses arising out of legal proceedings brought against them
by reason of their status or service as directors or officers. In addition,
Article VII of the Company's By-Laws provides for indemnification of directors,
officers and employees of the Company. Section 67 and the Company's By-Laws
generally provide that a director, officer or employee of the Company shall be
indemnified by the Company for all expenses and liabilities of legal proceedings
brought against him/her by reason of his/her status or service as a director,
officer or employee unless the director, officer or employee is adjudged not to
have acted in good faith in the reasonable belief that his/her action was in the
best interest of the Company or, to the extent that such matter relates to
service with respect to an employee benefit plan, in the best interests of the
participants or beneficiaries of such plan The Company's Restated Articles of
Organization also incorporate certain provisions permitted under the
Massachusetts General Laws relating to the liability of directors. The
provisions eliminate a director's liability for monetary damages for a breach of
fiduciary duty, including gross negligence, except in circumstances involving
certain wrongful acts, such as the breach of a director's duty of loyalty or
acts or omissions not in good faith or which involve intentional misconduct or a
knowing violation of law or authorization of distributions in violation of the
Restated Articles of Organization or of loans to officers or directors of the
Company or any transaction from which the director derived an improper personal
benefit. These provisions do not eliminate a director's duty of care. Moreover,
the provisions do not apply to claims against a director for violations of
certain laws, including federal securities laws.


ITEM 7.    EXEMPTION FROM REGISTRATION CLAIMED.

           Not applicable.


ITEM 8.    EXHIBITS.

           The following exhibits are filed as part of this Registration
           Statement:

           4.1    Restated Articles of Organization of the Company, as amended

           4.2    By-Laws of the Company (incorporated by reference to Exhibit
                  3.3 to the Company's Registration Statement on Form S-1 of the
                  Company, Registration No. 33-83916, filed with the Commission
                  on September 13, 1994)

           4.3    Specimen certificate representing Common Stock of the Company
                  (incorporated by reference to Exhibit 4.1 to the Company's
                  Registration Statement on Form S-1, Registration No. 33-83916,
                  filed with the Commission on September 13, 1994)

           4.4    Rights Agreement dated as of October 9, 1997, between the
                  Company and American Stock Transfer and Trust Company, as
                  Rights Agent (incorporated by reference to Exhibit 1 to the
                  Company's Registration Statement on Form 8-A, File No.
                  0-24786, filed with the Commission on October 10, 1997)


                                      II-2
<PAGE>   4

       4.5    Specimen certificate representing Rights to purchase Series A
              Participating Cumulative Preferred Stock of the Company (included
              as exhibit B to the Rights Agreement referenced in Exhibit 4.4)

       5.1    Opinion of Foley, Hoag & Eliot LLP

       10.1   Aspen Technology, Inc. 1998 Employee Stock Purchase Plan

       23.1   Consent of Arthur Andersen LLP

       23.2   Consent of Foley, Hoag & Eliot LLP (included in Exhibit 5.1)

       24.1   Power of Attorney (contained on the signature pages to this
              Registration Statement)


ITEM 9.  UNDERTAKINGS.

       1.     The undersigned Registrant hereby undertakes:

              (a) 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 the 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 the Registration Statement;

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

          provided, however, that paragraphs (i) and (ii) above do not apply if
          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 Exchange Act
          that are incorporated by reference herein.

              (b) 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 herein, and the offering of such securities at that time shall
          be deemed to be the initial bona fide offering thereof.

              (c) 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.

          2. 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 

                                      II-3
<PAGE>   5
Section 15(d) of the Exchange Act (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the Exchange
Act) 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.

           3. Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may 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 Commission such
indemnification is against public policy as expressed in the Securities Act of
1933 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 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.


                                      II-4
<PAGE>   6
                                   SIGNATURE

           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 Cambridge, Massachusetts, on this fifteenth day of
January, 1998.


                                 ASPEN TECHNOLOGY, INC.


                                 By: /s/ Lawrence B. Evans
                                    ----------------------------------------
                                    Lawrence B. Evans
                                    Chairman of the Board of Directors
                                      and Chief Executive Officer


                                POWER OF ATTORNEY

           KNOW ALL MEN BY THESE PRESENTS that each individual whose signature
appears below constitutes and appoints Lawrence B. Evans, Mary A. Palermo and
Stephen J. Doyle, and each of them, true and lawful attorneys-in-fact and agents
with full power of substitution, for and in name, place and stead, 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 all documents in connection therewith, with the Securities
and Exchange Commission, granting unto said attorneys-in-fact and agents, and
each of them, full power and authority to do and perform each and every act and
thing which they, or any of them, may deem necessary or advisable to be done in
connection with this Registration Statement, as fully to all intents and
purposes as he or she might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents or any of them, or any
substitute or substitutes for him, any or all of them, 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, as of this fifteenth day of January, 1998.

SIGNATURE                        TITLE


 /s/ LAWRENCE B. EVANS           Chairman of the Board of Directors and Chief
----------------------------     Executive Officer (Principal Executive Officer)
LAWRENCE B. EVANS


 /s/ MARY A. PALERMO             Executive Vice President (Principal Accounting
----------------------------     Officer and Principal Financial Officer)
MARY A. PALERMO

 /s/ JOSEPH F. BOSTON            Director
----------------------------     
JOSEPH F. BOSTON


                                      II-5
<PAGE>   7
SIGNATURE                        TITLE


 /s/ GRESHAM T. BREBACH, JR.     Director
------------------------------   
GRESHAM T. BREBACH, JR.


 /s/ DOUGLAS R. BROWN            Director
------------------------------  
DOUGLAS R. BROWN


 /s/ JOAN C. MCARDLE             Director 
------------------------------   
JOAN C. MCARDLE


 /s/ ALISON ROSS                 Director
------------------------------   
ALISON ROSS


                                      II-6
<PAGE>   8
                                  EXHIBIT INDEX

Exhibit No.       Description

      4.1         Restated Articles of Organization of Aspen Technology, Inc.,
                  as amended

      4.2         By-Laws of Aspen Technology, Inc. (incorporated by reference
                  to Exhibit 3.3 to Aspen Technology, Inc.'s Registration
                  Statement on Form S-1, Registration No. 33-83916, filed with
                  the Securities and Exchange Commission on September 13, 1994)

      4.3         Specimen certificate representing Common Stock of Aspen
                  Technology, Inc. (incorporated by reference to Exhibit 4.1 to
                  Aspen Technology, Inc.'s Registration Statement on Form S-1,
                  Registration No. 33-83916, filed with the Securities and
                  Exchange Commission on September 13, 1994)

      4.4         Rights Agreement dated as of October 9, 1997, between Aspen
                  Technology, Inc. and American Stock Transfer and Trust
                  Company, as Rights Agent (incorporated by reference to Exhibit
                  1 to Aspen Technology, Inc.'s Registration Statement on Form
                  8-A, File No. 0-24786, filed with the Securities and Exchange
                  Commission on October 10, 1997)

      4.5         Specimen certificate representing Rights to purchase Series A
                  Participating Cumulative Preferred Stock of Aspen Technology,
                  Inc. (included as exhibit B to the Rights Agreement referenced
                  in Exhibit 4.4)

      5.1         Opinion of Foley, Hoag & Eliot LLP

     10.1         Aspen Technology, Inc. 1998 Employee Stock Purchase Plan

     23.1         Consent of Arthur Andersen LLP

     23.2         Consent of Foley, Hoag & Eliot LLP (included in Exhibit 5.1)

     24.1         Power of Attorney (contained on the signature pages to this
                  Registration Statement)
[{"type": "S-8", "sequence": "1", "description": "ASPEN TECHNOLOGY, INC", "secsgml_size_bytes": 19028}]
{"company-data": {"conformed-name": "ASPEN TECHNOLOGY INC /MA/", "cik": "0000929940", "assigned-sic": "7371", "irs-number": "042739697", "state-of-incorporation": "MA", "fiscal-year-end": "0630"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-44575", "film-number": "98509623"}, "business-address": {"street1": "TEN CANAL PARK", "city": "CAMBRIDGE", "state": "MA", "zip": "02141", "phone": "6175770100"}, "mail-address": {"street1": "TEN CANAL PK", "city": "CAMBRIDGE", "state": "MA", "zip": "02141"}}
1
    AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JANUARY 20, 1998

                                                           Registration No. 333-

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM S-8

                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                             ASPEN TECHNOLOGY, INC.
             (Exact Name of Registrant as Specified in Its Charter)

     MASSACHUSETTS                                 04-2739697
(State or Other Jurisdiction of                   (I.R.S. Employer
Incorporation or Organization)                     Identification No.)

                 TEN CANAL PARK, CAMBRIDGE, MASSACHUSETTS 02141
               (Address of Principal Executive Offices) (Zip Code)

            ASPEN TECHNOLOGY, INC. 1998 EMPLOYEE STOCK PURCHASE PLAN
                            (Full Title of the Plan)

                                LAWRENCE B. EVANS
                     Chairman of the Board of Directors and
                            Chief Executive Officer
                             ASPEN TECHNOLOGY, INC.
                                 Ten Canal Park
                         Cambridge, Massachusetts 02141
                     (Name and Address of Agent for Service)

                                 (617) 949-1000
          (Telephone Number, Including Area Code, of Agent for Service)

                                 With copies to:

       STEPHEN J. DOYLE, ESQ.                       MARK L. JOHNSON, ESQ.
 Vice President and General Counsel               FOLEY, HOAG & ELIOT LLP
       ASPEN TECHNOLOGY, INC.                      One Post Office Square
           Ten Canal Park                       Boston, Massachusetts 02109
   Cambridge, Massachusetts 02141                      (617) 832-1000
           (617) 949-1000
CALCULATION OF REGISTRATION FEE
===================================================================================================================
               Title of                     Amount             Proposed               Proposed         Amount of
           Securities to be                 to be          Maximum Offering       Maximum Aggregate   Registration
              Registered                  Registered     Price Per Share(2)(3)    Offering Price(2)       Fee
-------------------------------------------------------------------------------------------------------------------
Common Stock, $.10 par value(1)        1,000,000 shares         $30.25               $30,250,000         $7,586
===================================================================================================================
(1)      Each share of Common Stock will be accompanied by one Right to purchase
         Series A Participating Cumulative Preferred Stock of the Registrant.
(2)      Estimated solely for the purpose of determining the registration fee. 
(3)      In accordance with Rules 457(c) and (h) under the Securities Act of
         1933, the calculation is based on 85% of the average of the high and
         low sale prices reported in the consolidated reporting system of the
         Nasdaq National Market on January 12, 1998.
2
                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3.    INCORPORATION OF DOCUMENTS BY REFERENCE.

           The following documents heretofore filed by Aspen Technology, Inc.
(the "Company") with the Securities and Exchange Commission (the "Commission")
pursuant to the Securities Exchange Act of 1934, as amended (the "Exchange Act")
are incorporated herein by reference:

           (1)    the Company's Annual Report on Form 10-K for the fiscal year
                  ended June 30, 1997, filed on September 29, 1997 pursuant to
                  Section 12 of Exchange Act;

           (2)    the Company's Quarterly Report on Form 10-Q for the quarterly
                  period ended September 30, 1997, filed on November 14, 1997
                  pursuant to Section 13 of the Exchange Act;

           (3)    the Company's Current Report on Form 8-K dated October 9,
                  1997, filed on October 10, 1997 pursuant to Section 13 of the
                  Exchange Act;

           (4)    the Company's definitive Proxy Statement dated October 29,
                  1997, filed on December 1, 1997 pursuant to Section 14 of
                  the Exchange Act; 

           (5)    the description of the Company's Common Stock contained in the
                  Registration Statement on Form 8-A filed on September 6, 1996
                  under Section 12 of the Exchange Act; and

           (6)    the description of the Company's Rights to purchase Series A
                  Participating Cumulative Preferred Stock contained in the
                  Registration Statement on Form 8-A filed on October 10, 1997
                  under Section 12 of the Exchange Act.

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

ITEM 4.    DESCRIPTION OF SECURITIES.

           Not applicable.

ITEM 5.    INTERESTS OF NAMED EXPERTS AND COUNSEL.

           Not applicable.

                                      II-1
3
ITEM 6.    INDEMNIFICATION OF DIRECTORS AND OFFICERS.

           Section 67 of Chapter 156B of the Massachusetts General Laws provides
a statutory framework covering indemnification of directors and officers against
liabilities and expenses arising out of legal proceedings brought against them
by reason of their status or service as directors or officers. In addition,
Article VII of the Company's By-Laws provides for indemnification of directors,
officers and employees of the Company. Section 67 and the Company's By-Laws
generally provide that a director, officer or employee of the Company shall be
indemnified by the Company for all expenses and liabilities of legal proceedings
brought against him/her by reason of his/her status or service as a director,
officer or employee unless the director, officer or employee is adjudged not to
have acted in good faith in the reasonable belief that his/her action was in the
best interest of the Company or, to the extent that such matter relates to
service with respect to an employee benefit plan, in the best interests of the
participants or beneficiaries of such plan The Company's Restated Articles of
Organization also incorporate certain provisions permitted under the
Massachusetts General Laws relating to the liability of directors. The
provisions eliminate a director's liability for monetary damages for a breach of
fiduciary duty, including gross negligence, except in circumstances involving
certain wrongful acts, such as the breach of a director's duty of loyalty or
acts or omissions not in good faith or which involve intentional misconduct or a
knowing violation of law or authorization of distributions in violation of the
Restated Articles of Organization or of loans to officers or directors of the
Company or any transaction from which the director derived an improper personal
benefit. These provisions do not eliminate a director's duty of care. Moreover,
the provisions do not apply to claims against a director for violations of
certain laws, including federal securities laws.

ITEM 7.    EXEMPTION FROM REGISTRATION CLAIMED.

           Not applicable.

ITEM 8.    EXHIBITS.

           The following exhibits are filed as part of this Registration
           Statement:

           4.1    Restated Articles of Organization of the Company, as amended

           4.2    By-Laws of the Company (incorporated by reference to Exhibit
                  3.3 to the Company's Registration Statement on Form S-1 of the
                  Company, Registration No. 33-83916, filed with the Commission
                  on September 13, 1994)

           4.3    Specimen certificate representing Common Stock of the Company
                  (incorporated by reference to Exhibit 4.1 to the Company's
                  Registration Statement on Form S-1, Registration No. 33-83916,
                  filed with the Commission on September 13, 1994)

           4.4    Rights Agreement dated as of October 9, 1997, between the
                  Company and American Stock Transfer and Trust Company, as
                  Rights Agent (incorporated by reference to Exhibit 1 to the
                  Company's Registration Statement on Form 8-A, File No.
                  0-24786, filed with the Commission on October 10, 1997)

                                      II-2
4

       4.5    Specimen certificate representing Rights to purchase Series A
              Participating Cumulative Preferred Stock of the Company (included
              as exhibit B to the Rights Agreement referenced in Exhibit 4.4)

       5.1    Opinion of Foley, Hoag & Eliot LLP

       10.1   Aspen Technology, Inc. 1998 Employee Stock Purchase Plan

       23.1   Consent of Arthur Andersen LLP

       23.2   Consent of Foley, Hoag & Eliot LLP (included in Exhibit 5.1)

       24.1   Power of Attorney (contained on the signature pages to this
              Registration Statement)

ITEM 9.  UNDERTAKINGS.

       1.     The undersigned Registrant hereby undertakes:

              (a) 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 the 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 the Registration Statement;

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

          provided, however, that paragraphs (i) and (ii) above do not apply if
          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 Exchange Act
          that are incorporated by reference herein.

              (b) 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 herein, and the offering of such securities at that time shall
          be deemed to be the initial bona fide offering thereof.

              (c) 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.

          2. 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 

                                      II-3
5
Section 15(d) of the Exchange Act (and, where applicable, each filing of an
employee benefit plan's annual report pursuant to Section 15(d) of the Exchange
Act) 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.

           3. Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may 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 Commission such
indemnification is against public policy as expressed in the Securities Act of
1933 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 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.

                                      II-4
6
                                   SIGNATURE

           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 Cambridge, Massachusetts, on this fifteenth day of
January, 1998.

                                 ASPEN TECHNOLOGY, INC.

                                 By: /s/ Lawrence B. Evans
                                    ----------------------------------------
                                    Lawrence B. Evans
                                    Chairman of the Board of Directors
                                      and Chief Executive Officer

                                POWER OF ATTORNEY

           KNOW ALL MEN BY THESE PRESENTS that each individual whose signature
appears below constitutes and appoints Lawrence B. Evans, Mary A. Palermo and
Stephen J. Doyle, and each of them, true and lawful attorneys-in-fact and agents
with full power of substitution, for and in name, place and stead, 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 all documents in connection therewith, with the Securities
and Exchange Commission, granting unto said attorneys-in-fact and agents, and
each of them, full power and authority to do and perform each and every act and
thing which they, or any of them, may deem necessary or advisable to be done in
connection with this Registration Statement, as fully to all intents and
purposes as he or she might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents or any of them, or any
substitute or substitutes for him, any or all of them, 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, as of this fifteenth day of January, 1998.

SIGNATURE                        TITLE

 /s/ LAWRENCE B. EVANS           Chairman of the Board of Directors and Chief
----------------------------     Executive Officer (Principal Executive Officer)
LAWRENCE B. EVANS

 /s/ MARY A. PALERMO             Executive Vice President (Principal Accounting
----------------------------     Officer and Principal Financial Officer)
MARY A. PALERMO

 /s/ JOSEPH F. BOSTON            Director
----------------------------     
JOSEPH F. BOSTON

                                      II-5
7
SIGNATURE                        TITLE

 /s/ GRESHAM T. BREBACH, JR.     Director
------------------------------   
GRESHAM T. BREBACH, JR.

 /s/ DOUGLAS R. BROWN            Director
------------------------------  
DOUGLAS R. BROWN

 /s/ JOAN C. MCARDLE             Director 
------------------------------   
JOAN C. MCARDLE

 /s/ ALISON ROSS                 Director
------------------------------   
ALISON ROSS

                                      II-6
8
                                  EXHIBIT INDEX

Exhibit No.       Description

      4.1         Restated Articles of Organization of Aspen Technology, Inc.,
                  as amended

      4.2         By-Laws of Aspen Technology, Inc. (incorporated by reference
                  to Exhibit 3.3 to Aspen Technology, Inc.'s Registration
                  Statement on Form S-1, Registration No. 33-83916, filed with
                  the Securities and Exchange Commission on September 13, 1994)

      4.3         Specimen certificate representing Common Stock of Aspen
                  Technology, Inc. (incorporated by reference to Exhibit 4.1 to
                  Aspen Technology, Inc.'s Registration Statement on Form S-1,
                  Registration No. 33-83916, filed with the Securities and
                  Exchange Commission on September 13, 1994)

      4.4         Rights Agreement dated as of October 9, 1997, between Aspen
                  Technology, Inc. and American Stock Transfer and Trust
                  Company, as Rights Agent (incorporated by reference to Exhibit
                  1 to Aspen Technology, Inc.'s Registration Statement on Form
                  8-A, File No. 0-24786, filed with the Securities and Exchange
                  Commission on October 10, 1997)

      4.5         Specimen certificate representing Rights to purchase Series A
                  Participating Cumulative Preferred Stock of Aspen Technology,
                  Inc. (included as exhibit B to the Rights Agreement referenced
                  in Exhibit 4.4)

      5.1         Opinion of Foley, Hoag & Eliot LLP

     10.1         Aspen Technology, Inc. 1998 Employee Stock Purchase Plan

     23.1         Consent of Arthur Andersen LLP

     23.2         Consent of Foley, Hoag & Eliot LLP (included in Exhibit 5.1)

     24.1         Power of Attorney (contained on the signature pages to this
                  Registration Statement)