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                                                                    EXHIBIT 10.1

                                Administaff, Inc.
                          19001 Crescent Springs Drive
                               Kingwood, TX 77339


February 16, 2001



American Express Travel Related Services Company, Inc.
American Express Tower
World Financial Center
200 Vesey Street
New York, New York 10285

Dear Sirs:

This letter sets forth the parties' agreement with respect to the purchase by
Administaff, Inc. ("ASF") from American Express Travel Related Services Company,
Inc. ("TRS") of up to 275,000 shares of ASF common stock, par value $0.01 per
share (the "Shares").

The parties agree as follows:

1.       ASF agrees to purchase up to 275,000 Shares from TRS at a purchase
         price per share equal to ninety-nine percent (99%) of the average of
         the closing sales prices of a Share as reported on the New York Stock
         Exchange composite transactions tape and reflected in the three star
         New York City edition of the Wall Street Journal over a twenty (20)
         trading-day period, of which the first ten trading days end on February
         16, 2001 and the second ten trading days commence on the day that ASF
         releases its earnings report for the fourth quarter of 2000.

2.       ASF's obligation to purchase the Shares is conditional upon (a) TRS
         first having exercised its warrant to purchase 800,000 shares of ASF
         common stock (the "Warrant Shares") at an exercise price of $20 per
         Warrant Share (subject to adjustment in accordance with the terms of
         the warrant) on or before March 10, 2001, the expiration date of the
         warrant; (b) the per share purchase price calculated as set forth in
         (1) above not exceeding $30; and (c) TRS notifying ASF that it is
         exercising its right to sell Shares under this Agreement not later than
         5:00 p.m. on March 12, 2001.

3.       Notwithstanding anything else to the contrary herein, TRS is not
         obligated to exercise the warrant; provided that if TRS does exercise
         the warrant and thereafter TRS desires to sell up to 275,000 Shares on
         or before March 12, 2001, TRS shall sell such Shares first pursuant to
         this Agreement.

4.       The closing of the sale and purchase will take place on March 12, 2001
         or such other day determined by TRS and ASF. At the closing, ASF will
         pay to TRS the aggregate


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         purchase price for the Shares by wire transfer of immediately available
         funds, and TRS will deliver to ASF certificates representing the
         Shares, duly endorsed for transfer. If so requested by TRS, the parties
         will net settle the exercise of the warrant and the sale and purchase
         of the Shares hereunder.

5.       ASF will pay all stamp, transfer and similar taxes in connection with
         the issuance of the Warrant Shares. TRS will pay all stamp, transfer
         and similar taxes, and all federal and state income taxes, in
         connection with TRS' ownership and exercise of the warrant and the sale
         of the Shares.

6.       The Shares TRS intends to sell are those common shares originally
         purchased from ASF in March 1998 and not the Warrant Shares. The
         parties shall execute any additional documents, if any, reasonably
         required for TRS to adequately identify the Shares sold by TRS
         hereunder as being the shares originally purchased from ASF in March
         1998.

7.       ASF will prepare a press release pursuant to which it will announce
         this agreement. Such release shall require the prior approval of TRS,
         such approval not to be unreasonably withheld.

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8.       This letter agreement shall be governed by the laws of the State of New
         York, without reference to conflict of laws rules.

                             ADMINISTAFF, INC.


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


AGREED:

AMERICAN EXPRESS TRAVEL RELATED
SERVICES COMPANY, INC.


By: /s/ Jay B. Stevelman
    ---------------------------------
Name:      Jay B. Stevelman
Title:     Treasurer