EXHIBIT 10.18

FOURTH AMENDMENT TO CREDIT AGREEMENT

       This Fourth Amendment (the “Fourth Amendment”) dated as of February 20,
2002 amends that certain $120,000,000 Multi-Currency Revolving Credit Agreement
dated as of January 9, 1998 among American Management Systems, Incorporated (as
a Borrower and the Guarantor), various other Borrowers, the Lenders named
therein and Bank of America, N.A., formerly NationsBank, N.A., as Administrative
Agent, and Wachovia Bank, N.A., as Documentation Agent, as amended by a certain
First Amendment to Credit Agreement dated as of March 16, 1998, a certain Second
Amendment to Credit Agreement dated as of March 21, 2001, and a certain Third
Amendment to Credit Agreement dated as of September 28, 2001, and as further
modified by a certain Waiver and Agreement dated as of July 25, 2001 (such
Credit Agreement, as amended or modified by such amendments and such waiver and
agreement, being referred to as the “Agreement”).

       WHEREAS, the Borrowers and the Guarantor have requested that the Lenders
amend certain provisions of the Agreement, and the Lenders are willing to amend
the Agreement as herein provided;

     NOW, THEREFORE, in consideration of the promises and the mutual covenants
contained herein, the Borrowers, the Guarantor and the Lenders agree as follows:

       1.     Definitions. Capitalized terms used herein and not otherwise
defined herein shall have the meanings assigned to them in the Agreement.

       2.     EBILTDA. The definition of “EBILTDA” in Section 1.1 of the
Agreement shall be amended, as of December 30, 2001, by adding the following
sentences at the end of such definition:

  “In addition, for the purposes of Section 5.2(b) hereof only, the amount of
EBILTDA computed with respect to any four-fiscal-quarter period that includes
the fiscal quarter ended December 31, 2001, shall be increased by adding back to
the amount otherwise calculated in accordance with the definition of EBILTDA the
amount, not to exceed $25,500,000, recorded as non-cash charges to income for
the fiscal quarter ended December 31, 2001.

          “Without limiting the generality of the preceding sentence, the
parties acknowledge that the adjustments to EBILTDA set forth in such sentence
shall not apply in determining the ratio of EBILTDA to Interest and Lease
Charges for purposes of the definition of ‘Applicable Rate.’ ”

 

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       3.     EBITDA. The definition of “EBITDA” in Section 1.1 of the Agreement
shall be amended, as of December 30, 2001, by adding the following sentences at
the end of such definition:

  “For the purposes of Section 5.2(a) hereof only, the amount of EBITDA computed
with respect to any four-fiscal-quarter period that includes the fiscal quarter
ended December 31, 2001, shall be increased by adding back to the amount
otherwise calculated in accordance with the definition of EBITDA the amount, not
to exceed $25,500,000, recorded as non-cash charges to income for the fiscal
quarter ended December 31, 2001.

       4.     Conditions Precedent. The effectiveness of this Fourth Amendment
shall be subject to fulfillment of the following conditions:

          (a)     The Administrative Agent shall have received an original of
this Fourth Amendment executed by AMS (as Borrower and as Guarantor), each of
the other Borrowers and the Required Lenders; and             (b)     AMS shall
have paid to the Administrative Agent and each Lender all amounts required to be
paid to such Persons pursuant to the fee letter dated February 20, 2002 between
Bank of America, N.A. and AMS.

       5.     Acknowledgement of Guarantor. The Guarantor affirms its
obligations under the Guaranty and consents to this Fourth Amendment.

       6.     Representations and Warranties. Each Borrower represents and
warrants to the Agents and each Lender as follows:

              6.1     Existence. Each of the Borrower and its Subsidiaries is a
corporation or partnership duly organized, validly existing and in good standing
under the Laws of the nation in which it is organized and any political
subdivision thereof, and is duly qualified to do business and in good standing
in each other nation and any political subdivision thereof where the nature or
extent of its business activities requires such qualification, except where the
failure to be so qualified and in good standing could not reasonably be expected
to have a Materially Adverse Effect.

              6.2     Power and Authority. Each of the Borrower and its
Subsidiaries has all requisite power and authority to own or lease its
properties, conduct its business as now conducted and to execute and deliver the
Fourth Amendment and to perform the Agreement as amended hereby.

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              6.3     Authorization and Enforceability. The execution, delivery
and performance of the Fourth Amendment have been duly authorized by all
necessary corporate or partnership action of each of the Borrower and its
Subsidiaries and require no consent of any Person which has not been obtained,
and the Fourth Amendment constitutes, and the Agreement as amended hereby
constitutes, valid and binding obligations of each of the Borrower and its
Subsidiaries party thereto, enforceable in accordance with their respective
terms, except as such enforceability may be limited by Debtor Relief Laws and by
general principles of equity.

              6.4     No Violation. The execution, delivery and performance of
the Fourth Amendment does not and will not violate any Borrower’s or any of its
Subsidiaries’ charter, bylaws, partnership agreement or other organizational
documents, any Laws applicable to such Borrower or any of its Subsidiaries or
any agreement to which such Borrower or any of its Subsidiaries is a party or by
which such Borrower or any of its Subsidiaries is bound, except for violations
of Laws or agreements which could not reasonably be expected to have a
Materially Adverse Effect.

              6.5     No Default. As of the date of this Fourth Amendment, no
Default Condition or Event of Default has occurred and is continuing under the
Agreement which has not been waived.

       7.     Cost and Expenses. AMS shall pay all reasonable out-of-pocket
costs, fees and expenses of the Administrative Agent incident to this Fourth
Amendment, including the reasonable fees, out-of-pocket expenses and other
disbursements of Smith Helms Mulliss & Moore, L.L.P., counsel for the
Administrative Agent, in connection with this Fourth Amendment.

       8.     Reaffirmation. Except as otherwise expressly amended by this
Fourth Amendment, the Agreement is and shall continue to be in full force and
effect in accordance with its terms. The parties hereto further agree that each
reference in any Loan Document to the “Agreement” or the “Loan Agreement” shall
be deemed to refer to the Agreement as amended by this Fourth Amendment and as
it may be amended, modified, supplemented, restated, renewed or extended from
time to time hereafter.

       9.     Miscellaneous.

              9.1     Governing Law. This Fourth Amendment shall be governed by,
and construed and interpreted in accordance with, the laws of the State of New
York.

              9.2     No Novation. The transactions described herein do not
constitute, and should not be construed to be, a novation of any indebtedness
outstanding under the Agreement.

              9.3     Successors and Assigns. This Fourth Amendment shall be
binding upon, inure to the benefit of and be enforceable by the Borrowers, the
Guarantor, the Agents, the Lenders and their respective successors and permitted
assigns.

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              9.4     Invalidity. If any provision of this Fourth Amendment
shall be held invalid by any court of competent jurisdiction, such holding shall
not invalidate any other provision hereof.

              9.5     Counterparts. This Fourth Amendment may be executed in
several counterparts, each of which shall be an original and all of which
together shall constitute but one and the same instrument.

              IN WITNESS WHEREOF, each Borrower, the Guarantor and the Lenders
parties hereto have caused this Fourth Amendment to be duly executed by their
respective authorized officers as of the day and year first above written.

  AMERICAN MANAGEMENT
SYSTEMS, INCORPORATED,
as Borrower and Guarantor

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  AMS MANAGEMENT SYSTEMS
DEUTSCHLAND GmbH,
as Borrower

  By:      /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  AMS MANAGEMENT SYSTEMS
EUROPE S.A./N.V.,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

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  AMS MANAGEMENT SYSTEMS U.K. Ltd.,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  AMS MANAGEMENT SYSTEMS CANADA
INC.,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  AMSY MANAGEMENT SYSTEMS
NETHERLANDS, B.V.,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  NORDIC BUSINESS MANAGEMENT
SYSTEMS AB,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

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  AMS MANAGEMENT SYSTEMS
AUSTRALIA PTY. LIMITED,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  AMS MANAGEMENT SYSTEMS
(SWITZERLAND) AG,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  AMS MANAGEMENT SYSTEMS ITALIA
S.p.A.,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  AMS MANAGEMENT SYSTEMS
FRANCE S.A.,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

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  AMS MANAGEMENT SYSTEMS
POLAND Sp. Z O.O.,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  AMERICAN MANAGEMENT SYSTEMS
PORTUGAL-CONSULTORIA E
DESENVOLVIMENTO DE SOFTWARE,
SOCIEDADE UNIPESSOAL IDA, as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

  AMS MANAGEMENT SYSTEMS
ESPAÑA, S.A.,
as Borrower

  By:     /s/Frank A. Nicolai     
Name:     Frank A. Nicolai     
Title:     Director     

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COMMONWEALTH OF VIRGINIA

CITY/COUNTY OF __________________

       The foregoing instrument was acknowledged before me in my jurisdiction
aforesaid this ____ day of __________, _______ by __________________, who is
____________ of AMS Management Systems Espana, S.A., for and on behalf of the
corporation.

  ____________________________
                Notary Public

My commission expires: _________________________

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  BANK OF AMERICA, N.A.,
as Administrative Agent and Lender

  By:     /s/Robert Martriello     
Name:     Robert Martriello     
Title:     Principal     

  WACHOVIA BANK, N.A.,
as Documentation Agent and Lender

  By:     /s/Elizabeth Witherspoon     
Name:     Elizabeth Witherspoon     
Title:     Vice President     

  BANK OF TOKYO – MITSUBISHI
TRUST COMPANY, as Lender

  By:     /s/Pamela Donnelly     
Name:     Pamela Donnelly     
Title:     Vice President     

  COMERICA BANK, as Lender

  By:     /s/Jeffrey M. Laffrehy     
Name:     Jeffrey M. Laffrehy     
Title:     Account Officer     

  KBC BANK N.V., as Lender

  By:     /s/Robert Snauffer     
Name:     Robert Snauffer     
Title:     First Vice President     

  By:     /s/Eric Raskin     
Name:     Eric Raskin     
Title:     Vice President     

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