Exhibit 21.1

SUBSIDIARIES OF ADMINISTAFF, INC.

• Administaff of Texas, Inc., a Delaware corporation and wholly owned subsidiary of Administaff, Inc.

• Administaff Enterprises, Inc., a Texas corporation and wholly owned subsidiary of Administaff of Texas, Inc.

• Administaff Partnerships Holding, Inc., a Delaware corporation and wholly owned subsidiary of Administaff of Texas, Inc.

• Administaff Captive Insurance Companies Limited, a Bermuda corporation and wholly owned subsidiary of Administaff Partnerships Holding, Inc.

• Administaff Business Services, L.P., a Delaware limited partnership, with Administaff of Texas, Inc. being a 1% general partner and Administaff Partnerships Holding, Inc. being a 99% limited partner.

• Administaff Retirement Services, L.P., a Delaware limited partnership, with Administaff of Texas, Inc. being a 1% general partner and Administaff Partnerships Holding, Inc. being a 99% limited partner.

• Administaff Services, L.P., a Delaware limited partnership, with Administaff of Texas, Inc. being a 1% general partner and Administaff Partnerships Holding, Inc. being a 99% limited partner.

• Administaff Partnerships Holding II, Inc., a Delaware corporation and wholly owned subsidiary of Administaff Services, L.P.

• Administaff GP, Inc., a Delaware corporation and wholly owned subsidiary of Administaff Services, L.P.

• Administaff Client Services, L.P., a Delaware limited partnership, with Administaff GP, Inc. being a 1% general partner and Administaff Partnerships Holding II, Inc. being a 99% limited partner.

• Administaff Companies, Inc., a Delaware corporation and wholly owned subsidiary of Administaff of Texas, Inc.

• Administaff Partnerships Holding III, Inc., a Delaware corporation and wholly owned subsidiary of Administaff Companies, Inc.

• Administaff Companies II, L.P., a Delaware limited partnership, with Administaff Companies, Inc. being a 1% general partner and Administaff Partnerships Holding III, Inc. being a 99% limited partner.

• Administaff Insurance Services, L.L.C., a Delaware limited liability corporation and wholly owned subsidiary of Administaff Companies II, L.P.

• Administaff Holdings, LLC, a Delaware limited liability corporation and wholly owned subsidiary of Administaff of Texas, Inc.

ExpensAble, Inc. a California Corporation and wholly owned subsidiary of Administaff of Texas, Inc.