<PAGE>   1
     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON AUGUST 13, 1999
                                                           REGISTRATION NO. 333-

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                             ----------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933



                             ----------------------


                                ADMINISTAFF, INC.
             (Exact name of registrant as specified in its charter)

            DELAWARE                                              76-0479645
(State or other jurisdiction of                               (I.R.S. Employer
 incorporation or organization)                              Identification No.)

                          19001 CRESCENT SPRINGS DRIVE
                           KINGWOOD, TEXAS 77339-3802
          (Address, including zip code, of Principal Executive Offices)


                      ADMINISTAFF, INC. 1997 INCENTIVE PLAN

                ADMINISTAFF, INC. NONQUALIFIED STOCK OPTION PLAN
                            (Full title of the plan)

                               JOHN H. SPURGIN, II
                                ADMINISTAFF, INC.
                          19001 CRESCENT SPRINGS DRIVE
                           KINGWOOD, TEXAS 77339-3802
                                 (281) 358-8986
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)



                                    copy to:

                               G. MICHAEL O'LEARY
                             ANDREWS & KURTH L.L.P.
                             600 TRAVIS, SUITE 4200
                              HOUSTON, TEXAS 77002
                                 (713) 220-4200

                             ----------------------


                         CALCULATION OF REGISTRATION FEE


<TABLE>
<CAPTION>
======================================================================================================================
                                                                                         PROPOSED
                                                                                         MAXIMUM
                                                    AMOUNT            PROPOSED          AGGREGATE          AMOUNT OF
                                                     TO BE         OFFERING PRICE        OFFERING         REGISTRATION
     TITLE OF SECURITIES TO BE REGISTERED         REGISTERED        PER SHARE(1)         PRICE(1)             FEE
----------------------------------------------------------------------------------------------------------------------
<S>                                               <C>              <C>                 <C>                <C>
Common Stock, par value $0.01 per share            1,200,000           $15.09          $18,108,000         $ 5,034.02
======================================================================================================================
</TABLE>

(1)  Estimated solely for the purpose of calculating the registration fee
     pursuant to Rule 457(h), based upon the average of the high and low prices
     per share for August 11, 1999 on the New York Stock Exchange as reported in
     The Wall Street Journal on August 12, 1999.

================================================================================
<PAGE>   2
                                     PART I

                INFORMATION REQUIRED IN SECTION 10(A) PROSPECTUS

     The document(s) containing the information specified in Part I of Form S-8
will be sent or given to participants as specified by Rule 428(b)(1) of the
Securities Act of 1933, as amended (the "Securities Act"). Such documents need
not be filed with the Securities and Exchange Commission (the "Commission")
either as a part of this Registration Statement or as prospectuses or prospectus
supplements pursuant to Rule 424. These documents and the documents incorporated
herein by reference pursuant to Item 3 of Part II of this Registration
Statement, taken together, constitute a prospectus that meets the requirements
of Section 10(a) of the Securities Act (the "Prospectus").

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

         Administaff, Inc. (the "Company") hereby incorporates by reference the
following documents listed below. In addition, all documents subsequently filed
by the Company pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities
Exchange Act of 1934 (the "Exchange Act") (prior to the filing of a
post-effective amendment which indicates that all the 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 thereof from the date of filing of such documents.

         (a)      The Company's Annual Report on Form 10-K for the year ended
                  December 31, 1998.

         (b)      The Company's Quarterly Report on Form 10-Q for the Quarter
                  ended March 31, 1999.

         (c)      The description of the Company's common stock, par value $0.01
                  per share, contained in the Company's Registration Statement
                  on Form 8-A (No. 13998) filed with the Commission on October
                  6, 1995 pursuant to Section 12 of the Exchange Act.

         All documents filed by the Company pursuant to Section 13(a), 13(c), 14
or 15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act")
subsequent to the date of this Registration Statement and prior to the filing of
a post-effective amendment which indicates that all securities offered hereby
have been sold or which deregisters all such securities then remaining unsold,
shall be deemed to be incorporated by reference herein 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 herein by reference shall
be deemed to be modified or superseded for purposes of the Registration
Statement and the 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 the Registration Statement or the
Prospectus.

ITEM 4. DESCRIPTION OF SECURITIES.

         The information required by Item 4 is not applicable to this
Registration Statement since the class of securities to be offered is registered
under Section 12 of the Exchange Act.
<PAGE>   3
ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.

         The information required by Item 5 is not applicable to this
Registration Statement.

ITEM 6. INDEMNIFICATION OF OFFICERS AND DIRECTORS.

         Subsection (a) of Section 145 of the General Corporation Law of the
State of Delaware empowers a corporation to indemnify any person who was or is a
party or 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, against expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement actually and reasonably
incurred by him in connection with such action, suit or proceeding 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.

         Subsection (b) of Section 145 empowers a corporation to indemnify any
person who was or is a party or is threatened to be made a party to any
threatened, pending or completed action, or suit by or in the right of the
corporation to procure a judgment in its favor by reason of the fact that such
person acted in any of the capacities set forth above, against expenses
(including attorneys' fees) actually and reasonably incurred by him in
connection with the defense or settlement of such action or suit 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, except that no indemnification may be made in
respect of any claim, issue or matter as to which such person shall have been
made to be liable to the corporation unless and only to the extent that the
Court of Chancery or the court in which such action or suit was brought shall
determine upon application that, despite the adjudication of liability but in
view of all the circumstances of the case, such person is fairly and reasonably
entitled to indemnity for such expenses which the Court of Chancery or such
other court shall deem proper.

         Section 145 further provides that to the extent a director or officer
of a corporation has been successful on the merits or otherwise in the defense
of any action, suit or proceeding referred to in subsections (a) and (b) of
Section 145 in the defense of any claim, issue or matter therein, he shall be
indemnified against expenses (including attorneys' fees) actually and reasonably
incurred by him in connection therewith; that indemnification provided for by
Section 145 shall not be deemed exclusive of any other rights to which the
indemnified party may be entitled; that indemnification provided for by Section
145 shall, unless otherwise provided when authorized or ratified, continue as to
a person who has ceased to be a director, officer, employee or agent and shall
inure to the benefit of such person's heirs, executors and administrators; and
empowers the corporation to purchase and maintain insurance on behalf of a
director or officer of the corporation against any liability asserted against
him and incurred by him in any such capacity, or arising out of his status as
such whether or not the corporation would have the power to indemnify him
against such liabilities under Section 145.

         Section 102(b)(7) of the General Corporation Law of the State of
Delaware provides that a certificate of incorporation may contain a provision
eliminating or limiting the personal liability of a director to the corporation
or its stockholders for monetary damages for breach of fiduciary duty as a
director provided that such provision shall not eliminate or limit the liability
of a director (i) for any breach of the director's duty of loyalty to the
corporation or its stockholders, (ii) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 of the Delaware General Corporation Law, or (iv) for any transaction
from which the director derived an improper personal benefit.

         Article Eleventh of the Company's Certificate of Incorporation states
that:
<PAGE>   4
         No director of the Corporation shall be personally liable to the
Corporation or its stockholders for monetary damages for breach of fiduciary
duty by such director as a director; provided, however, that this Article
Eleventh shall not eliminate or limit the liability of a director to the extent
provided by applicable law (i) for any breach of the director's duty of loyalty
to the Corporation or its stockholders, (ii) for acts or omissions not in good
faith or which involve intentional misconduct or a knowing violation of law,
(iii) under Section 174 of the General Corporation Law of the State of Delaware
or (iv) for any transaction from which the director derived an improper personal
benefit. No amendment to or repeal of this Article Eleventh shall apply to, or
have any effect on, the liability or alleged liability of any director of the
Corporation for or with respect to any facts or omissions of such director
occurring prior to such amendment or repeal. If the General Corporation Law of
the State of Delaware is amended to authorize corporate action further
eliminating or limiting the personal liability of directors, then the liability
of a director of the Corporation shall be eliminated or limited to the fullest
extent permitted by the General Corporation Law of the State of Delaware, as so
amended.

         In addition, Article VI of the Company's Bylaws further provides that
the Company shall indemnify its officers, directors and employees to the fullest
extent permitted by law.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

         The information required by Item 7 is not applicable to this
Registration Statement because the class of securities to be offered is
registered under Section 12 of the Exchange Act.

ITEM 8. EXHIBITS.

   Exhibit
   Number     Description

     5.1      Opinion of Andrews & Kurth L.L.P.

    23.1      Consent of Andrews & Kurth L.L.P. (included in Exhibit 5.1)

    23.2      Consent of Ernst & Young LLP

    24.1      Power of Attorney (included in signature page)

    99.1      Administaff, Inc. 1997 Incentive Plan

    99.2      First Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.3      Second Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.4      Third Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.5      Fourth Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.6      Administaff, Inc. Nonqualified Stock Option Plan

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:
<PAGE>   5
                           (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 this 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 this Registration Statement;

                  Provided, however, that paragraphs (a)(1)(i) and (a)(1)(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 Company pursuant to Section
                  13 or Section 15(d) of the Securities Exchange Act of 1934
                  that are incorporated by reference in the 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
Company's annual report pursuant to Section 13(a) or 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 therein, and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof.

         (c) Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Company pursuant to the foregoing provisions, or otherwise, the
Company 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 Company of expenses
incurred or paid by a director, officer or controlling person of the Company 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 Company 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.
<PAGE>   6
                                   SIGNATURES

         The Registrant. Pursuant to the requirements of the Securities Act of
1933, 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 Houston, State of Texas, on the 13th day of
August, 1999.


                                  ADMINISTAFF, INC.



                                  By: /s/ RICHARD G. RAWSON
                                     -------------------------------------------
                                     Richard G.  Rawson
                                     Executive Vice President of Administration,
                                     Chief Financial Officer and Treasurer


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned officers
and directors of Administaff, Inc. (the "Company"), hereby constitutes and
appoints Paul J. Sarvadi and Richard G. Rawson, or either of them (with full
power to each of them to act alone), his true and lawful attorney-in-fact and
agent, with full power of substitution, for him and on his behalf and in his
name, place and stead, in any and all capacities, to sign, execute and file this
Registration Statement under the Securities Act of 1933, as amended, and any or
all amendments (including, without limitation, post-effective amendments), with
all exhibits and any and all documents required to be filed with respect
thereto, with the Securities and Exchange Commission or any regulatory
authority, granting unto 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 and about the premises in order to
effectuate the same, as fully to all intents and purposes as he himself might or
could do, if personally present, hereby ratifying and confirming all that said
attorneys-in-fact and agents, or any of them, or their substitute or
substitutes, may lawfully do or cause to be done.

         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 the 13th day of August, 1999.

<TABLE>
<CAPTION>
          SIGNATURE                            TITLE
          ---------                            -----
<S>                              <C>


/s/ PAUL J. SARVADI
------------------------------   President, Chief Executive Officer and
Paul J. Sarvadi                  Director  (Principal Executive Officer)


/s/ RICHARD G. RAWSON
------------------------------   Executive Vice President of Administration,
Richard G. Rawson                Chief Financial Officer, Treasurer and Director
                                 (Principal Financial Officer)


/s/ SAMUEL G. LARSON
------------------------------   Vice President of Finance and Controller
Samuel G.  Larson                (Principal Accounting Officer)
</TABLE>
<PAGE>   7
<TABLE>
<S>                              <C>
-----------------------------    Director
Jack M. Fields, Jr.


/s/ PAUL S. LATTANZIO
-----------------------------    Director
Paul S. Lattanzio


/s/ LINDA FAYNE LEVINSON
-----------------------------    Director
Linda Fayne Levinson


/s/ STEVE ALESIO
-----------------------------    Director
Steve Alesio



-----------------------------    Director
Michael W. Brown
</TABLE>
<PAGE>   8
                                 EXHIBIT INDEX

<TABLE>
<CAPTION>
   EXHIBIT
   NUMBER     DESCRIPTION
   -------    -----------
<S>           <C>
     5.1      Opinion of Andrews & Kurth L.L.P.

    23.1      Consent of Andrews & Kurth L.L.P. (included in Exhibit 5.1)

    23.2      Consent of Ernst & Young LLP

    24.1      Power of Attorney (included in signature page)

    99.1      Administaff, Inc. 1997 Incentive Plan

    99.2      First Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.3      Second Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.4      Third Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.5      Fourth Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.6      Administaff, Inc. Nonqualified Stock Option Plan
</TABLE>
[{"type": "S-8", "sequence": "1", "description": "ADMINISTAFF, INC.", "secsgml_size_bytes": 22431}]
{"company-data": {"conformed-name": "ADMINISTAFF INC \\DE\\", "cik": "0001000753", "assigned-sic": "7363", "irs-number": "760479645", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-85151", "film-number": "99688458"}, "business-address": {"street1": "19001 CRESCENT SPRINGS DR", "city": "KINGWOOD", "state": "TX", "zip": "77339", "phone": "7133588986"}, "mail-address": {"street1": "19001 CRESCENT SPRINGS DR", "city": "KINGWOOD", "state": "TX", "zip": "77339"}}
1
     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON AUGUST 13, 1999
                                                           REGISTRATION NO. 333-

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                             ----------------------

                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                             ----------------------

                                ADMINISTAFF, INC.
             (Exact name of registrant as specified in its charter)

            DELAWARE                                              76-0479645
(State or other jurisdiction of                               (I.R.S. Employer
 incorporation or organization)                              Identification No.)

                          19001 CRESCENT SPRINGS DRIVE
                           KINGWOOD, TEXAS 77339-3802
          (Address, including zip code, of Principal Executive Offices)

                      ADMINISTAFF, INC. 1997 INCENTIVE PLAN

                ADMINISTAFF, INC. NONQUALIFIED STOCK OPTION PLAN
                            (Full title of the plan)

                               JOHN H. SPURGIN, II
                                ADMINISTAFF, INC.
                          19001 CRESCENT SPRINGS DRIVE
                           KINGWOOD, TEXAS 77339-3802
                                 (281) 358-8986
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

                                    copy to:

                               G. MICHAEL O'LEARY
                             ANDREWS & KURTH L.L.P.
                             600 TRAVIS, SUITE 4200
                              HOUSTON, TEXAS 77002
                                 (713) 220-4200

                             ----------------------

                         CALCULATION OF REGISTRATION FEE
======================================================================================================================
                                                                                         PROPOSED
                                                                                         MAXIMUM
                                                    AMOUNT            PROPOSED          AGGREGATE          AMOUNT OF
                                                     TO BE         OFFERING PRICE        OFFERING         REGISTRATION
     TITLE OF SECURITIES TO BE REGISTERED         REGISTERED        PER SHARE(1)         PRICE(1)             FEE
----------------------------------------------------------------------------------------------------------------------
Common Stock, par value $0.01 per share            1,200,000           $15.09          $18,108,000         $ 5,034.02
======================================================================================================================
(1)  Estimated solely for the purpose of calculating the registration fee
     pursuant to Rule 457(h), based upon the average of the high and low prices
     per share for August 11, 1999 on the New York Stock Exchange as reported in
     The Wall Street Journal on August 12, 1999.

================================================================================
2
                                     PART I

                INFORMATION REQUIRED IN SECTION 10(A) PROSPECTUS

     The document(s) containing the information specified in Part I of Form S-8
will be sent or given to participants as specified by Rule 428(b)(1) of the
Securities Act of 1933, as amended (the "Securities Act"). Such documents need
not be filed with the Securities and Exchange Commission (the "Commission")
either as a part of this Registration Statement or as prospectuses or prospectus
supplements pursuant to Rule 424. These documents and the documents incorporated
herein by reference pursuant to Item 3 of Part II of this Registration
Statement, taken together, constitute a prospectus that meets the requirements
of Section 10(a) of the Securities Act (the "Prospectus").

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

         Administaff, Inc. (the "Company") hereby incorporates by reference the
following documents listed below. In addition, all documents subsequently filed
by the Company pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities
Exchange Act of 1934 (the "Exchange Act") (prior to the filing of a
post-effective amendment which indicates that all the 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 thereof from the date of filing of such documents.

         (a)      The Company's Annual Report on Form 10-K for the year ended
                  December 31, 1998.

         (b)      The Company's Quarterly Report on Form 10-Q for the Quarter
                  ended March 31, 1999.

         (c)      The description of the Company's common stock, par value $0.01
                  per share, contained in the Company's Registration Statement
                  on Form 8-A (No. 13998) filed with the Commission on October
                  6, 1995 pursuant to Section 12 of the Exchange Act.

         All documents filed by the Company pursuant to Section 13(a), 13(c), 14
or 15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act")
subsequent to the date of this Registration Statement and prior to the filing of
a post-effective amendment which indicates that all securities offered hereby
have been sold or which deregisters all such securities then remaining unsold,
shall be deemed to be incorporated by reference herein 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 herein by reference shall
be deemed to be modified or superseded for purposes of the Registration
Statement and the 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 the Registration Statement or the
Prospectus.

ITEM 4. DESCRIPTION OF SECURITIES.

         The information required by Item 4 is not applicable to this
Registration Statement since the class of securities to be offered is registered
under Section 12 of the Exchange Act.
3
ITEM 5. INTERESTS OF NAMED EXPERTS AND COUNSEL.

         The information required by Item 5 is not applicable to this
Registration Statement.

ITEM 6. INDEMNIFICATION OF OFFICERS AND DIRECTORS.

         Subsection (a) of Section 145 of the General Corporation Law of the
State of Delaware empowers a corporation to indemnify any person who was or is a
party or 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, against expenses (including attorneys'
fees), judgments, fines and amounts paid in settlement actually and reasonably
incurred by him in connection with such action, suit or proceeding 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.

         Subsection (b) of Section 145 empowers a corporation to indemnify any
person who was or is a party or is threatened to be made a party to any
threatened, pending or completed action, or suit by or in the right of the
corporation to procure a judgment in its favor by reason of the fact that such
person acted in any of the capacities set forth above, against expenses
(including attorneys' fees) actually and reasonably incurred by him in
connection with the defense or settlement of such action or suit 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, except that no indemnification may be made in
respect of any claim, issue or matter as to which such person shall have been
made to be liable to the corporation unless and only to the extent that the
Court of Chancery or the court in which such action or suit was brought shall
determine upon application that, despite the adjudication of liability but in
view of all the circumstances of the case, such person is fairly and reasonably
entitled to indemnity for such expenses which the Court of Chancery or such
other court shall deem proper.

         Section 145 further provides that to the extent a director or officer
of a corporation has been successful on the merits or otherwise in the defense
of any action, suit or proceeding referred to in subsections (a) and (b) of
Section 145 in the defense of any claim, issue or matter therein, he shall be
indemnified against expenses (including attorneys' fees) actually and reasonably
incurred by him in connection therewith; that indemnification provided for by
Section 145 shall not be deemed exclusive of any other rights to which the
indemnified party may be entitled; that indemnification provided for by Section
145 shall, unless otherwise provided when authorized or ratified, continue as to
a person who has ceased to be a director, officer, employee or agent and shall
inure to the benefit of such person's heirs, executors and administrators; and
empowers the corporation to purchase and maintain insurance on behalf of a
director or officer of the corporation against any liability asserted against
him and incurred by him in any such capacity, or arising out of his status as
such whether or not the corporation would have the power to indemnify him
against such liabilities under Section 145.

         Section 102(b)(7) of the General Corporation Law of the State of
Delaware provides that a certificate of incorporation may contain a provision
eliminating or limiting the personal liability of a director to the corporation
or its stockholders for monetary damages for breach of fiduciary duty as a
director provided that such provision shall not eliminate or limit the liability
of a director (i) for any breach of the director's duty of loyalty to the
corporation or its stockholders, (ii) for acts or omissions not in good faith or
which involve intentional misconduct or a knowing violation of law, (iii) under
Section 174 of the Delaware General Corporation Law, or (iv) for any transaction
from which the director derived an improper personal benefit.

         Article Eleventh of the Company's Certificate of Incorporation states
that:
4
         No director of the Corporation shall be personally liable to the
Corporation or its stockholders for monetary damages for breach of fiduciary
duty by such director as a director; provided, however, that this Article
Eleventh shall not eliminate or limit the liability of a director to the extent
provided by applicable law (i) for any breach of the director's duty of loyalty
to the Corporation or its stockholders, (ii) for acts or omissions not in good
faith or which involve intentional misconduct or a knowing violation of law,
(iii) under Section 174 of the General Corporation Law of the State of Delaware
or (iv) for any transaction from which the director derived an improper personal
benefit. No amendment to or repeal of this Article Eleventh shall apply to, or
have any effect on, the liability or alleged liability of any director of the
Corporation for or with respect to any facts or omissions of such director
occurring prior to such amendment or repeal. If the General Corporation Law of
the State of Delaware is amended to authorize corporate action further
eliminating or limiting the personal liability of directors, then the liability
of a director of the Corporation shall be eliminated or limited to the fullest
extent permitted by the General Corporation Law of the State of Delaware, as so
amended.

         In addition, Article VI of the Company's Bylaws further provides that
the Company shall indemnify its officers, directors and employees to the fullest
extent permitted by law.

ITEM 7. EXEMPTION FROM REGISTRATION CLAIMED.

         The information required by Item 7 is not applicable to this
Registration Statement because the class of securities to be offered is
registered under Section 12 of the Exchange Act.

ITEM 8. EXHIBITS.

   Exhibit
   Number     Description

     5.1      Opinion of Andrews & Kurth L.L.P.

    23.1      Consent of Andrews & Kurth L.L.P. (included in Exhibit 5.1)

    23.2      Consent of Ernst & Young LLP

    24.1      Power of Attorney (included in signature page)

    99.1      Administaff, Inc. 1997 Incentive Plan

    99.2      First Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.3      Second Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.4      Third Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.5      Fourth Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.6      Administaff, Inc. Nonqualified Stock Option Plan

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:
5
                           (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 this 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 this Registration Statement;

                  Provided, however, that paragraphs (a)(1)(i) and (a)(1)(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 Company pursuant to Section
                  13 or Section 15(d) of the Securities Exchange Act of 1934
                  that are incorporated by reference in the 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
Company's annual report pursuant to Section 13(a) or 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 therein, and the offering of such securities at that time
shall be deemed to be the initial bona fide offering thereof.

         (c) Insofar as indemnification for liabilities arising under the
Securities Act of 1933 may be permitted to directors, officers and controlling
persons of the Company pursuant to the foregoing provisions, or otherwise, the
Company 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 Company of expenses
incurred or paid by a director, officer or controlling person of the Company 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 Company 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.
6
                                   SIGNATURES

         The Registrant. Pursuant to the requirements of the Securities Act of
1933, 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 Houston, State of Texas, on the 13th day of
August, 1999.

                                  ADMINISTAFF, INC.

                                  By: /s/ RICHARD G. RAWSON
                                     -------------------------------------------
                                     Richard G.  Rawson
                                     Executive Vice President of Administration,
                                     Chief Financial Officer and Treasurer

                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned officers
and directors of Administaff, Inc. (the "Company"), hereby constitutes and
appoints Paul J. Sarvadi and Richard G. Rawson, or either of them (with full
power to each of them to act alone), his true and lawful attorney-in-fact and
agent, with full power of substitution, for him and on his behalf and in his
name, place and stead, in any and all capacities, to sign, execute and file this
Registration Statement under the Securities Act of 1933, as amended, and any or
all amendments (including, without limitation, post-effective amendments), with
all exhibits and any and all documents required to be filed with respect
thereto, with the Securities and Exchange Commission or any regulatory
authority, granting unto 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 and about the premises in order to
effectuate the same, as fully to all intents and purposes as he himself might or
could do, if personally present, hereby ratifying and confirming all that said
attorneys-in-fact and agents, or any of them, or their substitute or
substitutes, may lawfully do or cause to be done.

         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 the 13th day of August, 1999.
SIGNATURE                            TITLE
          ---------                            -----
/s/ PAUL J. SARVADI
------------------------------   President, Chief Executive Officer and
Paul J. Sarvadi                  Director  (Principal Executive Officer)

/s/ RICHARD G. RAWSON
------------------------------   Executive Vice President of Administration,
Richard G. Rawson                Chief Financial Officer, Treasurer and Director
                                 (Principal Financial Officer)

/s/ SAMUEL G. LARSON
------------------------------   Vice President of Finance and Controller
Samuel G.  Larson                (Principal Accounting Officer)
7
-----------------------------    Director
Jack M. Fields, Jr.

/s/ PAUL S. LATTANZIO
-----------------------------    Director
Paul S. Lattanzio

/s/ LINDA FAYNE LEVINSON
-----------------------------    Director
Linda Fayne Levinson

/s/ STEVE ALESIO
-----------------------------    Director
Steve Alesio

-----------------------------    Director
Michael W. Brown
8
                                 EXHIBIT INDEX
EXHIBIT
   NUMBER     DESCRIPTION
   -------    -----------
5.1      Opinion of Andrews & Kurth L.L.P.

    23.1      Consent of Andrews & Kurth L.L.P. (included in Exhibit 5.1)

    23.2      Consent of Ernst & Young LLP

    24.1      Power of Attorney (included in signature page)

    99.1      Administaff, Inc. 1997 Incentive Plan

    99.2      First Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.3      Second Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.4      Third Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.5      Fourth Amendment to the Administaff, Inc. 1997 Incentive Plan

    99.6      Administaff, Inc. Nonqualified Stock Option Plan