1 Exhibit 23.1 CONSENT OF INDEPENDENT ACCOUNTANTS We consent to the incorporation by reference in this Registration Statement of American Management Systems, Incorporated on Form S-8 of our reports dated February 17, 1999, appearing in and incorporated by reference in the Annual Report on Form 10-K of American Management Systems, Incorporated for the year ended December 31, 1998. /s/ DELOITTE & TOUCHE LLP Washington, D.C. August 17, 1999