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                                                                   EXHIBIT 10.21
                       AGREEMENT TO RESTRUCTURE AND EXTEND

The NATIONAL FIRE PROTECTION ASSOCIATION (Landlord) and ATLANTIC DATA SERVICES,
INC. (Tenant), being the parties to a Lease Agreement dated April 1, 1995
(Lease), as that Lease has been amended and extended, as hereinafter set out, do
hereby enter this Agreement to Restructure and Extend the Lease as amended for
the purposes and under the conditions as hereinafter set out.

BACKGROUND

The parties entered a lease agreement dated April 1, 1995 for lease by the
Tenant of 21,192 Rentable Square Feet (RSF) of space on the third floor (the
Premises) at the Landlord's building located at Batterymarch Park, Quincy,
Massachusetts (the Building). That lease was amended as follows:

         a)       First Amendment dated July 31, 1995, adding 1,337 RSF to the
                  Premises

         b)       Second Amendment dated January 15, 1997, adding 1,213 RSF to
                  the Premises

         c)       Third Amendment dated October 15, 1998, adding 1,540 RSF to
                  the Premises

         d)       Fourth Amendment dated May 1, 1999, adding 2,043 RSF to the
                  Premises such additional space to be carpeted by the Landlord

The Lease as amended was thereafter extended pursuant to an AGREEMENT FOR
EXERCISE OF OPTION dated November 23, 1999, for an addition term of five years
commencing April 1, 2000, and ending March 31, 2005.

The parties have now agreed to restructure and extend the Lease, as such was
amended and extended, in the following manner (i) the Tenant will surrender and
the Landlord will accept 10,949 RSF as of January 1, 2004, (ii) the Tenant will
surrender and the Landlord will accept an additional 1,540 RSF as of April 1,
2005, through the remainder of the terms; and (iii) the parties have agreed to
extend the Lease for another term of five years beginning April 1, 2005 and
ending March 31, 2010.

The Premises will consist of 16,376 RSF as of January 1, 2004 and 14,836 RSF as
of April 1, 2005.

This background statement is not intended to be part of the terms and conditions
of this Agreement to Restructure and Extend, nevertheless the parties may make
reference to the figures included herein when convenient to explain, but not to
contradict the hereinafter set out terms and conditions.

TERMS AND CONDITIONS:

1.       AMENDMENT OF PREMISES AREA: Section 1.2 of The Lease (which term shall
         mean the Lease as amended by the above referenced amendments and
         extended by the above referenced Exercise of Option), the Premises
         Rentable Area, is hereby amended by deletion of the following areas of
         rentable square feet, (See Exhibit A) and replacement with the amended
         area of rentable square feet as of the following dates.

         1/1/04, delete 10,949 RSF from the total RSF leaving a total of 16,376
         RSF
         3/31/05 delete 1,540 RSF from the total RSF leaving a total of 14,836
         RSF

         The Landlord will be responsible for reasonable costs to demise the
         Premises Rentable Area.

2.       EXTENSION OF TERM: The lease as so amended is hereby extended for an
         additional term of five (5) years beginning April 1, 2005 and running
         through March 31, 2010. (hereinafter the Extended Lease Term)

3.       EXTENDED LEASE TERM BASIC RENT: During the Extended Term, the Basic
         Rent is hereby set forth as follows:

         4/1/05 - 3/31/06           $20.25 per RSF
         4/1/06 - 3/31/07           $21.25 per RSF
         4/1/07 - 3/31/08           $22.25 per RSF
         4/1/08 - 3/31/09           $23.25 per RSF
         4/1/08 - 3/31/10           $24.25 per RSF

         Sections 2.3 and 3.2 of the Lease are hereby deleted.

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4.       ELECTRICITY: Notwithstanding the responsibility of the Landlord under
         Section 7.5 of the Lease to supply electricity to the premises, the
         Tenant shall be charged, as additional rent and in addition to any
         other escalation charges, the cost of electricity to the premises for
         lights, outlets, and operation of the Variable-air-volume (VAV) boxes.
         The charge is established at $1.00 per RSF per year. Said charge will
         be effective as of April 1, 2005. Tenant shall maintain its
         responsibility for metered electricity service to its computer room.

5.       BASE OPERATING EXPENSES AND BASE TAXES: The base operating expenses
         shall be the actual expenses for Calendar year 2004, and the Base Taxes
         shall be the actual real estate taxes for Fiscal Year 2004.

6.       CREDIT FOR IMPROVEMENTS: Tenant has available a tenant improvement
         credit of $35,502.00, which may be used by Tenant for renovations or
         improvements within its Premises during the term of the Lease as here
         extended.

7.       RENTAL FORBEARANCE: The Landlord shall not charge the Tenant any base
         rent for the period January 1, 2004 through February 14, 2004.

8.       PARKING: As of January 1, 2004, Tenant shall have 8 reserved marked
         parking spaces in specific locations as determined by the Landlord.

9.       BROKERAGE: Section 14.22 of the Lease is hereby deleted and replaced
         with the following Section:

         14.22    BROKERAGE

         Tenant warrants and represents that Tenant has dealt with no broker in
         connection with the consummation of this Lease other than The Conrad
         Group and, in the event that any brokerage makes claim against Landlord
         predicated upon dealings with Tenant in consummation hereof, Tenant
         agrees to defend the same and indemnify Landlord against any such
         claim. Landlord represents that it has dealt with and been represented
         in this transaction by Insignia/ESG, Inc. Landlord agrees that it will
         compensate Insignia/ESG, Inc. and The Conrad Group by the payment, to
         be divided equally, of one full fee determined in accordance with its
         agreement with Insignia/ESG, but that such full fee shall be based on
         the schedule for the Extended Lease Term only.

10.      RIGHT OF FIRST REFUSAL: Section 14.24, Right of First Refusal, is
         hereby deleted and shall have no further force or effect.

11.      OPTION TO EXTEND: Article XV of the Lease is hereby deleted and
         replaced by the following:

                                   ARTICLE XV
                                OPTION TO EXTEND

         15.1     TENANT'S OPTION

                  Provided that at the time of exercise there exists no Default
                  of Tenant and that this Lease is still in full force and
                  effect, Tenant shall have the right and option to extend the
                  Term of this Lease of one extended term of three years (the
                  Extended Option Term) commencing on the day immediately
                  succeeding the expiration date of the Extended Lease Term and
                  ending at the close of the day on the last day of the
                  Thirty-Sixth calendar month thereafter. Tenant shall exercise
                  such option to extend by giving written notice to Landlord not
                  later than twelve months prior to the expiration of the
                  Extended Lease Term. The giving of such notice by Tenant shall
                  automatically extend the Term of this Lease for the Extended
                  Option Term and no instrument of renewal need to be executed.
                  In the event that Tenant fails to give such notice to
                  Landlord, this Lease shall automatically terminate at the end
                  of the Extended Lease Term and Tenant shall have no further
                  option to extend the Term of this Lease. The Extended Lease
                  Term shall be on all the terms and conditions of this Lease as
                  Restructured and Extended except that the provisions of the
                  Section 15.1 shall not be applicable and Basic Rent shall be
                  as determined pursuant to paragraph 15.2 hereof.

         15.2     EXTENDED TERM RENT

                  The Basic Rent for the Extended Term shall be the greater of,
                  the fair market rental value of the Premises as of the
                  commencement of the Extended Option Term, determined without
                  regard to Tenant's right to extend, as agreed by the parties;
                  or the then applicable Base Rental Rate, as per the Extended
                  Lease Term Rent.

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12.      EFFECT OF PRIOR DOCUMENTS: This AGREEMENT TO RESTRUCTURE AND EXTEND is
         entered into predicated upon and acknowledging the above noted Original
         Lease, Amendments to the Original Lease, and the Agreement for Exercise
         of Option. This agreement shall be considered to supercede all said
         documents where there are superceding provisions. All provision of any
         of the said prior documents contrary to the provisions hereof shall be
         and hereby are declared void. All provisions of the prior documents not
         contrary to this AGREEMENT TO RESTRUCTURE AND EXTEND, shall be and
         hereby are considered to be affirmed.

         IN WITNESS WHEREOF, Landlord and Tenant have caused this Lease to be
duly executed, under seal, by persons hereunto duly authorized, in multiple
copies, each to be considered an original hereof, as of the date first set forth
above.

LANDLORD:                                        TENANT:

NATIONAL FIRE PROTECTION                         ATLANTIC DATA SERVICES
ASSOCIATION, INC.

By: /s/ Bruce Mullen                             By: /s/ Paul K. McGrath
    ---------------------------------                --------------------------
Title: Senior Vice President and CFO             Title: Senior Vice President,
Date: May 5, 2003                                CFO and Treasurer
                                                 Date: May 5, 2003