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                                                                     Exhibit 4.1

                                VOTING AGREEMENT

      This VOTING AGREEMENT (this "AGREEMENT") is made and entered into as of
July 21, 2003 (the "EFFECTIVE DATE"), by and between Atlantic Data Services,
Inc. a Massachusetts corporation ("ADS"), and the undersigned stockholder of ADS
("STOCKHOLDER").

                                    RECITALS

      A. This Agreement is entered into in connection with that certain
Agreement and Plan of Merger dated as of even date herewith, as amended from
time to time (the "MERGER AGREEMENT"), by and between ADS and ADS Acquisition
Company LLC, a Massachusetts limited liability company ("LLC"), pursuant to
which LLC will merge with and into ADS, the separate corporate existence of LLC
will cease and ADS will continue as the surviving corporation, all upon and
subject to the terms and conditions of the Merger Agreement and certain other
agreements entered into thereunder (the "MERGER"). Capitalized terms that are
used in this Agreement which are not otherwise defined herein will have the
meanings given such terms in the Merger Agreement.

      B. As of the Effective Date of this Agreement, Stockholder owns in the
aggregate (including shares held both beneficially and of record and other
shares held either beneficially or of record) the number of shares of ADS
capital stock set forth below Stockholder's name on the signature page of this
Agreement (all such shares, together with any shares of capital stock of ADS
that may hereafter be acquired by Stockholder, being collectively referred to
herein as the "SUBJECT SHARES").

      C. Stockholder is entering into this Agreement as a material inducement
to, and in consideration of, ADS' willingness to enter into the Merger
Agreement.

                                    AGREEMENT

      The parties to this Agreement, intending to be legally bound, agree as
follows:

      1. TRANSFER OF SUBJECT SHARES.

            1.1 NO DISPOSITION OR ENCUMBRANCE OF SUBJECT SHARES. Stockholder
agrees with ADS that, prior to the Expiration Date (as defined below),
Stockholder will not, directly or indirectly, sell, transfer, exchange, pledge,
encumber or otherwise dispose of, or in any other way reduce Stockholder's risk
of ownership or investment in, or make any offer or agreement relating to any of
the foregoing with respect to, any Subject Shares; provided, however, that
notwithstanding the foregoing, the Stockholder may transfer all or any portion
of the Subject Shares (a) by will or intestacy, (b) to the Stockholder's
members, partners, affiliates or immediate family members (including
Stockholder's spouse, lineal descendants, father, mother, brother, sister or
first cousin, and father, mother, brother or sister of Stockholder's spouse),
(c) to LLC or any parent, subsidiary or affiliate of LLC, or (d) to a trust, the
beneficiaries of which are such Stockholder and/or members of Stockholder's
immediate family; provided, further, that the donee or transferee agrees in
writing to be bound by the
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foregoing in the same manner as Stockholder. As used herein, the term
"EXPIRATION DATE" means the earlier to occur of (i) such time as the Merger
Agreement is terminated in accordance with its terms, (ii) the Closing Date (as
defined in the Merger Agreement), or (iii) the date of execution of a written
agreement by ADS and Stockholder to terminate this Agreement.

            1.2 TRANSFER OF VOTING RIGHTS. Stockholder agrees that, prior to the
Expiration Date, Stockholder will not deposit any of the Subject Shares into a
voting trust or grant a proxy or enter into an agreement of any kind with
respect to the voting of any of the Subject Shares, except in connection with a
vote to approve the transaction contemplated by the Merger Agreement.

      2. VOTING OF SUBJECT SHARES. Stockholder agrees that, prior to the
Expiration Date, at any meeting of the stockholders of ADS, however called, and
in any action taken by the written consent of stockholders of ADS without a
meeting, unless otherwise directed in writing by ADS, Stockholder will vote the
Subject Shares:

                  (i) in favor of the Merger, the execution, delivery and
performance by ADS of the Merger Agreement and the adoption and approval of the
terms thereof and in favor of each of the other actions and agreements
contemplated by the Merger Agreement and any action required in furtherance
hereof and thereof; and

                  (ii) against any proposal for any recapitalization, merger,
sale of a substantial portion of ADS' assets or other business combination
between ADS and any person or entity (other than the Merger) or any other action
or agreement that would result in a breach of any covenant, representations or
warranty or other obligation or agreement of ADS under the Merger Agreement or
which could result in any of the conditions to ADS' obligations under the Merger
Agreement not being fulfilled (an "ALTERNATIVE TRANSACTION"), unless such
Alternative Transaction has been approved by the Board of Directors of ADS upon
the recommendation of the Independent Committee. The Stockholder shall not
commit or agree to take any action inconsistent with the foregoing. The
Stockholder acknowledges receipt and review of a copy of the Merger Agreement.

            Notwithstanding the foregoing, Stockholder shall have no obligation
to vote any of the Subject Shares as set forth above if in the reasonable
judgment of Stockholder there has occurred any event that has had, or would be
reasonably likely to have, a Material Adverse Effect on the Company. Prior to
the Expiration Date, Stockholder will not enter into any agreement or
understanding with any person or entity to vote or give instructions in any
manner inconsistent with this Section 2.

      3. REPRESENTATIONS, WARRANTIES AND COVENANTS OF STOCKHOLDER. Stockholder
hereby represents, warrants and covenants as follows:

            3.1 AUTHORITY, ENFORCEABILITY. Stockholder has full power and
authority to enter into, execute, deliver and perform Stockholder's obligations
under this Agreement and to make the representations, warranties and covenants
contained herein, and that all corporate or similar action required for the
authorization, execution, delivery and the performance of all


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obligations of Stockholder under this Agreement and the agreements contemplated
hereby have been obtained. This Agreement has been duly executed and delivered
by Stockholder and constitutes a legal, valid and binding obligation of
Stockholder, enforceable against Stockholder in accordance with its terms.

            3.2 SUBJECT SHARES OWNED. As of the Effective Date of this
Agreement, Stockholder owns in the aggregate (including shares held both
beneficially and of record and other shares held either beneficially or of
record) the number of shares of ADS capital stock set forth below Stockholder's
name on the signature page of this Agreement free and clear from any
encumbrance, and does not directly or indirectly own, either beneficially or of
record, any shares of capital stock of ADS, or rights to acquire any shares of
capital stock of ADS, or other securities of ADS, other than the Subject Shares
set forth below Shareholder's name on the signature page hereof.

            3.3 FURTHER ASSURANCES. Stockholder agrees to execute and deliver
any additional documents and instruments, and take such actions as are
reasonably necessary to carry out the purposes and intent of this Agreement.

      4. MISCELLANEOUS.

            4.1 SEVERABILITY. If any provision of this Agreement, or the
application thereof, will for any reason and to any extent be invalid or
unenforceable, the remainder of this Agreement and application of such provision
to other persons or circumstances will be interpreted so as reasonably to effect
the intent of the parties hereto.

            4.2 AMENDMENT AND WAIVER. This Agreement or any provision hereof may
be amended, modified, superseded, canceled, renewed, waived or extended only by
an agreement in writing executed by ADS and Stockholder. The waiver by a party
of any breach hereof or default in the performance hereof will not be deemed to
constitute a waiver of any other default or any succeeding breach or default.

            4.3 ASSIGNMENT. This Agreement and all rights and obligations
hereunder may not be transferred or assigned by ADS or Stockholder at any time
without the prior written consent of ADS and Stockholder; provided, however,
that Stockholder may transfer or assign this Agreement and all rights and
obligations hereunder as set forth in Section 1.1 without the prior written
consent of ADS. This Agreement will be binding upon, and inure to the benefit
of, the persons or entities who are permitted, by the terms of this Agreement,
to be successors, assigns and personal representatives of the respective parties
hereto.

            4.4 GOVERNING LAW. The validity, interpretation and enforcement of
this Agreement will be governed by and construed in accordance with the internal
laws of The Commonwealth of Massachusetts, excluding that body of laws
pertaining to conflict of laws.

            4.5 COSTS OF ENFORCEMENT. If any party to this Agreement seeks to
enforce its rights under this Agreement by legal proceedings or otherwise, the
non-prevailing party will pay


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all costs and expenses incurred by the prevailing party, including, without
limitation, all reasonable attorneys' and experts' fees.

            4.6 COUNTERPARTS. This Agreement may be executed in counterparts,
each of which will be deemed an original but all of which, taken together,
constitute one and the same agreement.

            4.7 ENTIRE AGREEMENT; TERMINATION. This Agreement and the documents
referred to herein constitute the entire agreement and understanding of the
parties with respect to the subject matter of this Agreement, and supersede all
prior understandings and agreements, whether oral or written, between or among
the parties hereto with respect to the specific subject matter hereof. This
Agreement shall only terminate on the Expiration Date.

            4.8 SPECIFIC PERFORMANCE; INJUNCTIVE RELIEF. The parties hereto
acknowledge that each party will be irreparably harmed and that there will be no
adequate remedy at law for a violation of any of the covenants or agreements set
forth herein. Therefore, it is agreed that, in addition to any other remedies
that may be available to each party upon any such violation, each party shall
have the right to enforce such covenants and agreements by specific performance,
injunctive relief or by any other means available at law or in equity.

            4.9 NOTICES. All notices, requests, claims, demands and other
communications hereunder shall be in writing and sufficient if delivered in
person, by facsimile, or sent by overnight courier (prepaid) to the respective
parties as follows:

      If to ADS:                 Members of the Independent Committee
                                 of the Board of Directors
                                 One Batterymarch Park
                                 Atlantic Data Services, Inc.
                                 Quincy, MA 02169
                                 Attention:        Richard D. Driscoll, Chairman
                                 Telephone:        (617) 770-3333
                                 Facsimile:        (617) 689-1105

      With copy to:              McDermott, Will & Emery
                                 28 State Street
                                 Boston, MA 02109
                                 Attention:        John J. Egan III, P.C.
                                 Telephone:        (617) 535-4040
                                 Facsimile:        (617) 535-3800


      If to the Stockholder:     To the addresses for notice set forth on the
                                 last page hereof.

or to such other address as any party may have furnished to the other in writing
in accordance herewith, except that notices of change of address shall only be
effective upon receipt.


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      IN WITNESS WHEREOF, the undersigned parties have executed this Agreement
as of the Effective Date.

ATLANTIC DATA SERVICES, INC.

By:
    -------------------------------------------------

Name:
      -----------------------------------------------

Title:
       ----------------------------------------------

STOCKHOLDER

(INDIVIDUAL SIGNATURE BLOCK):             (ENTITY SIGNATURE BLOCK):

                                          --------------------------------------
                                           (please print or type complete name
                                                       of entity)

                                          By:
----------------------------------------     -----------------------------------
            (signature)                                  (signature)

Name:                                     Name:
      ----------------------------------       ---------------------------------
       (please print or type full name)         (please print or type full name)

                                          Title:
                                                --------------------------------
                                                (please print or type full name)


ADS Common Stock (No. of Shares):
                                 -----------------------------------------------
ADS Common Stock held indirectly (No. of Shares):
                                                 -------------------------------
Rights to Acquire ADS Common Stock (No. of Shares):
                                                   -----------------------------

Address:                                  With a copy of any notice to:

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TELEPHONE:                                TELEPHONE:
          ------------------------------            ----------------------------

FACSIMILE:                                FACSIMILE:
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                      [SIGNATURE PAGE TO VOTING AGREEMENT]

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