Exhibit 5

        [LETTER HEAD OF SHAW, PITTMAN, POTTS & TROWBRIDGE APPEARS HERE]

                                January 24, 1996

American Management Systems,
 Incorporated
4050 Legato Road
Fairfax, Virginia  22033


Ladies and Gentlemen:

     We have acted as counsel to American Management Systems, Incorporated (the
"Company"), a Delaware corporation, in connection with the registration of
150,000 shares of its Common Stock, $0.01 par value per share (the "Common
Stock"), pursuant to a Registration Statement on Form S-8 under the Securities
Act of 1933, as amended (the "Registration Statement"), and the Outside
Directors Stock-for-Fees Plan (the "Plan").

     Based upon examination and review of (i) the Second Restated Certificate of
Incorporation of the Company, (ii) the Bylaws of the Company, as amended, and
(iii) the resolutions of the Board of Directors of the Company dated February
24, 1995, we are of the opinion that the Common Stock has been duly authorized
for issuance by the Company, and that upon issuance and delivery in accordance
with the Plan referred to in the Registration Statement, the Common Stock will
be validly issued, fully paid and nonassessable.

     Our opinions stated in this letter are based on the General Corporation Law
of the State of Delaware in effect on the date of this letter.  The opinions
expressed in this letter are limited to the matters set forth herein, and no
other opinions should be inferred beyond the matters expressly stated.
 
     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement.


                                       Very truly yours,

                                       /S/ SHAW, PITTMAN, POTTS & TROWBRIDGE

                                       SHAW, PITTMAN, POTTS & TROWBRIDGE