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                                                                       EXHIBIT 1


                       AMENDMENT NO. 3 TO RIGHTS AGREEMENT

         THIS AMENDMENT NO. 3 TO RIGHTS AGREEMENT (this "Amendment"), dated as
of July 22, 1999 is entered into and effectuated by Administaff, Inc., a
Delaware corporation (the "Company"), and Harris Trust and Savings Bank, as
rights agent (the "Rights Agent"), pursuant to Section 27 of the Rights
Agreement, dated as of February 4, 1998 (the "Rights Agreement"), between the
Company and the Rights Agent, at the Company's direction. Capitalized terms used
but not defined herein are used as defined in the Rights Agreement.

                                    RECITALS:

         WHEREAS, Section 27 of the Rights Agreement provides that the Company
may in its sole discretion, and the Rights Agent shall if the Company so
directs, supplement or amend any provision of the Rights Agreement in any
respect without the approval of the holders of the Rights; and

         WHEREAS, on July 12, 1999 the Company received a copy of a Schedule
13D/A (the "Schedule 13D/A") filed by the "Gerhard Stockholders" (defined below)
indicating that such group beneficially owned approximately 23.3% of the
outstanding shares of the Company's common stock; and

         WHEREAS, subsequent to the filing of the Schedule 13D/A, the Gerhard
Stockholders have indicated by letter to the Board of Directors of the Company
that, prior to July 30, 1999, the Gerhard Stockholders intend (a) to sell the
number of shares on the open market that would reduce their beneficial ownership
of the Company's outstanding shares to approximately 20.5% and (b) to the extent
that the open market sales are not sufficient to reduce their beneficial
ownership to 20.5%, to sell the number of shares back to the Company, at a
mutually agreed upon price, that would reduce to the beneficial ownership of the
Gerhard Stockholders to the greater of (i) 2,929,800 shares and (ii) 20.5% of
the Company's outstanding shares; and

         WHEREAS, at a meeting on July 22, 1999, the Board of Directors
determined that it is in the best interests of the Company for the Gerhard
Stockholders to continue to constitute an Exempt Person (which excludes persons
who would otherwise be deemed to be Acquiring Persons, as that term is defined
in the Rights Agreement) for a period up to and including August 2, 1999,
notwithstanding the recent increased beneficial ownership (above the thresholds
currently designated in the Rights Agreement for the Gerhard stockholders) of
the Gerhard Stockholders;

         WHEREAS, in accordance with Section 27 of the Rights Agreement, the
Company has delivered a certificate from an appropriate officer of the Company
stating that this Amendment is in compliance with the terms of Section 27 of the
Rights Agreement.

         NOW, THEREFORE, the Rights Agreement is hereby amended as follows:


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1.       Effective as of the date first set forth above, Section 35 of the
Rights Agreement shall read in its entirety as follows:

         Section 35. Extension of Status of Gerhard Stockholders as a Exempt
Person. Notwithstanding the provisions of Section 1(p) and Section 3 of this
Agreement, unless the Board of Directors otherwise specifies, the Gerhard
Stockholders shall not cease to be an Exempt Person during the period up to and
including August 2, 1999.

2.       Except to the extent amended by this Amendment, the Rights Agreement
shall continue in full force and effect.



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         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed and attested, all as of the day and year first above written.


                                    ADMINISTAFF, INC.


                                    By: /s/ Paul J. Sarvadi
                                        --------------------------------------
                                        Paul J. Sarvadi
                                        President and Chief Executive Officer


                                    HARRIS TRUST AND SAVINGS BANK
                                    as Rights Agent


                                    By: /s/ Ray Rosenbaum
                                        --------------------------------------
                                        Ray Rosenbaum
                                        Vice President