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                                                                    EXHIBIT 10.4

                             STOCKHOLDERS AGREEMENT

      This Stockholders Agreement (this "Agreement") is entered into as of June
27, 2001 by and among PRA HOLDINGS, INC., a Delaware corporation (the
"Company"), GENSTAR CAPITAL PARTNERS III, L.P., a Delaware limited partnership
("Genstar"), STARGEN III, L.P., a Delaware limited partnership ("Stargen," and,
together with Genstar, the "Genstar Investors"), each of the Persons listed on
Exhibit A hereto (the "Additional Investors"), each of the individuals listed on
Exhibit B hereto (the "Management Investors"), and each of the warrantholders
listed on Exhibit C attached hereto (including warrantholders who acquire
warrants to purchase capital stock of the Company after the date hereof and
execute a counterpart to this Agreement or otherwise agree to be bound by this
Agreement, the "Warrantholders"). The Genstar Investors, the Management
Investors, the Additional Investors, the Warrantholders and any other Person
that executes a counterpart to this Agreement from time to time in such capacity
are collectively referred to as the "Stockholders" and individually as a
"Stockholder."

                                    RECITALS

      WHEREAS, the Company and others are parties to an Agreement and Plan of
Merger, dated as of May 16, 2001 (the "Merger Agreement"), pursuant to which
certain of the Management Investors are acquiring certain shares of common stock
of the Company, par value $.01 per share (the "Common Stock"). The execution and
delivery of this Agreement by the Company and by those Management Investors is a
condition to the consummation of the Merger (as defined in the Merger
Agreement).

      WHEREAS, the Company and the Genstar Investors are parties to a Securities
Purchase Agreement, dated as of June 26, 2001 (the "Purchase Agreement")
pursuant to which the Genstar Investors are acquiring certain shares of Common
Stock. The execution and delivery of this Agreement by the Company and the
parties hereto is a condition to the closing of the Purchase Agreement.

      WHEREAS, the Company and the Additional Investors are parties to a
Subscription Agreement, dated as of June 26, 2001 (the "Subscription Agreement")
pursuant to which the Additional Investors are acquiring certain shares of
Common Stock. The execution and delivery of this Agreement by the Company and
the parties hereto is a condition to the closing of the Subscription Agreement.

      WHEREAS, the Company has granted, and may in future grant, Options (as
defined herein) to the Management Investors pursuant to certain employee stock
option plans.

      WHEREAS, the Company has issued Warrants (as defined herein) to the
Warrantholders in connection with certain financing transactions by and among
the Company and the Warrantholders (or their Affiliates) entered into
concurrently herewith.

      WHEREAS, the Company and the Stockholders desire to enter into this
Agreement for the purposes, among others, of (i) limiting the manner and terms
by which the Stockholders' Common Stock may be transferred, (ii) assuring
continuity in the management and ownership of the Company and (iii) establishing
the composition of the Company's Board of Directors (the "Board").

                                    AGREEMENT

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      To implement the foregoing and in consideration of the mutual covenants
and agreements contained herein, the parties hereto agree as follows:

      1 Definitions.

            As used in this Agreement, the following capitalized terms shall
have the following meanings:

            "Affiliate" means with respect to a Stockholder any other Person,
directly or indirectly controlling, controlled by or under common control with
such Stockholder.

            "Assumed Options" means all Options that prior to the Merger were
options to purchase shares of common stock of PRA International, Inc and which
were assumed by the Company, and converted into Options, pursuant to the Merger.

            "BHCA" means the Bank Holding Company Act of 1956, as amended, any
successor statute and the regulations of the FRB thereunder.

            "BHC Holder" means a Stockholder which is (a) a "bank holding
company" as defined in the BHCA, (b) a foreign banking organization subject to
the non-banking provisions of the BHCA under the International Banking Act of
1978, as amended, or any successor statute, or (c) a non-bank subsidiary (as
such term is defined in the BHCA) or either of the foregoing.

            "Call Shares" means all Options issued pursuant to the 2001 PRA
International, Inc. Option Plan, all shares of Common Stock issued upon exercise
of such Options, and all equity securities of the Company acquired by the
Management Investors after the date hereof (and any securities of the Company
issued after the date hereof which are convertible into, or any Options,
Warrants or other rights which are exercisable or exchangeable for, equity
securities of the Company), including shares of Common Stock issued upon
exercise of Options granted after the date hereof, provided, however, that
Assumed Options, shares of Common Stock issued upon exercise of Assumed Options,
and Rollover Shares shall not be Call Shares for the purposes of this Agreement

            "Competitor" means any business or Person that is a contract
research organization or performs or provides similar clinical drug or
pharmaceutical development services to or for any other Person on a contract or
outsourced basis and businesses complimentary and ancillary thereto.

            "Fiscal Quarter" means a fiscal quarter of the Company and its
Subsidiaries in any Fiscal Year.

            "Fiscal Year" means the fiscal year of Company and its Subsidiaries
established by the Board. For purposes of this Agreement, any particular Fiscal
Year shall be designated by reference to the calendar year in which such Fiscal
Year ends.

            "FRB" means the Board of Governors of the Federal Reserve System or
any successor agency having regulatory authority under the BHCA.

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            "Management Investor" means the individuals listed on Exhibit B, and
any other member of the management of the Company who becomes a stockholder of
the Company and a party to this Agreement pursuant to Section 17 hereof.

            "New Securities" means (i) any Common Stock or other equity
securities of the Company, (ii) any securities of the Company which are
convertible into, or any Options, Warrants or other rights which are exercisable
or exchangeable for, such Common Stock or such other equity securities of the
Company.

            "Options" means any options to purchase Common Stock or other equity
securities issued by the Company.

            "Person" means an individual, a partnership, a corporation, a
limited liability company, an association, a joint stock company, a trust, a
joint venture, an unincorporated organization and a governmental entity or any
department, agency or political subdivision thereof.

            "Public Offering" means the issuance and sale of shares of Common
Stock to the public pursuant to a registration statement under the Securities
Act which has been declared effective by the Securities and Exchange Commission
(other than a registration statement on Form S-8 or any other similar form).

            "Public Sale" means any sale of Shares to the public pursuant to a
Public Offering or pursuant to the provisions of Rule 144, or any successor
provision thereto, adopted under the Securities Act.

            "Qualified Public Offering" means a Public Offering (which may be
the initial Public Offering) having an aggregate offering value of at least
$25,000,000.

            "Registration Rights Agreement" means that certain Registration
Rights Agreement of even date herewith, among the Company, the Genstar
Investors, Capital D'Amerique CDPQ Inc., and certain other parties thereto.

            "Rollover Shares" means those shares of Common Stock acquired by the
Management Investors pursuant to the Merger in exchange for shares of common
stock of PRA International, Inc.

            "Securities Act" means the Securities Act of 1933, as amended from
time to time.

            "Shares" means (i) any Common Stock purchased or otherwise acquired
by any Stockholder, (ii) any Common Stock issued or issuable directly or
indirectly upon exercise of Warrants or Options and (iii) any equity securities
issued or issuable with respect to the securities referred to in clauses (i) and
(ii) above by way of stock dividend or stock split or in connection with a
combination of shares, recapitalization, merger, consolidation or other
reorganization. For purposes of this Agreement, any Person who holds Warrants or
Options or any other equity security convertible into or exercisable for Shares
or any right to acquire directly or indirectly such Shares shall be deemed to be
the holder of the Shares issuable directly or indirectly upon conversion of the
Warrants or Options in connection with the transfer thereof

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or otherwise and regardless of any restriction or limitation on the conversion
thereof and whether or not such conversion, exercise or acquisition has actually
been effected.

            "Significant Holder" means (a) each Genstar Investor, (b) each
Additional Investor which holds at least 2% of the total amount of Common Stock
then outstanding, (c) each Additional Investor who holds at least 2% of the
total amount of Common Stock outstanding as of the date hereof (so long as such
Additional Investor then holds 10,000 Shares (as appropriately adjusted for
stock splits, stock dividends, and the like)), and (d) each person who is a
Management Investor as of the date hereof (so long as such Management Investor
then holds 10,000 Shares and/or Options to purchase 10,000 Shares (as
appropriately adjusted for stock splits, stock dividends, and the like));
provided that the Stockholder who is proposing to sell his, her or its Shares
pursuant to Section 5 hereof shall not be a Significant Holder with respect to
such proposed sale.

            "Subsidiary" means, with respect to the Company, any corporation,
partnership, trust, limited liability company, association, joint venture or
other business entity of which the Company or one or more of its other
Subsidiaries or a combination thereof, owns or controls, directly or indirectly,
more than 50% of the total voting power of shares of stock or other ownership
interests entitled (without regard to the occurrence of any contingency) to vote
in the election of the members of the board of directors or other body having
the power to direct or cause the direction of the management and policies of
such corporation, partnership, trust, limited liability company, association,
joint venture or other business entity.

            "Voting Securities" shall have the meaning given to such term under
12 CFR Section 225.2(q) of the regulations of the FRB, or any successor
regulations of the FRB under the BHCA.

            "Warrants" means any warrants to acquire Common Stock issued by the
Company.

      2 Restriction on Transfer of Shares.

            (a) No Stockholder shall sell, transfer, assign, pledge, hypothecate
or otherwise dispose of (whether with or without consideration and whether
voluntarily or by operation of law) any interest in his, her or its Shares (a
"Transfer") at any time, except pursuant to clause (c) of this Section 2,
Sections 3, 4, 5, 7 or 9 hereof, or, with respect to any Stockholder other than
the Genstar Investors and their Affiliates, without the prior written approval
of Genstar, which approval shall not be unreasonably withheld or delayed (but
which approval may be conditioned upon the transferee agreeing to be bound by
this Agreement); provided, however, that Genstar may withhold such approval in
its sole discretion with regard to any proposed Transfer to a Competitor, or an
Affiliate of a Competitor, of the Company; provided further that Genstar shall
provide each Significant Holder with prompt notice following any such Transfer
approval.

            (b) Any attempt to Transfer any Shares not in compliance with this
Agreement shall be null and void and neither the Company nor any transfer agent
shall give any effect in the Company's stock records to such attempted Transfer.

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            (c) The restrictions set forth in this Section 2 shall not apply
with respect to any Transfer of Shares by any Stockholder (i) to the Company
pursuant to Section 7 or Section 5 (except Transfers from the Genstar Investors
and their Affiliates), (ii) in the case of any Stockholder who is a natural
person, pursuant to applicable laws of descent and distribution or among such
Stockholder's Family Group or Affiliates, as applicable, (iii) in the case of
any Stockholder, to its respective officers, directors, employees, partners or
members or Affiliates, and (iv) as to any Stockholder, pursuant to a Public Sale
(each such Transfer collectively referred to herein as a "Permitted Transfer"
and each such transferee referred to herein as a "Permitted Transferee");
provided that the restrictions contained in this Section 2 shall continue to be
applicable to the Shares after any such Transfer (other than a Transfer to the
Company or as provided in Section 2(e) hereof); provided, further that the
transferees of such Shares (other than in the case where the Company is the
transferee and other than a Transfer pursuant to a Public Sale) shall have
agreed in writing to be bound by the provisions of this Agreement affecting the
Shares so transferred and shall execute and deliver to the Company and the other
Stockholders a counterpart of this Agreement; provided, however, that
notwithstanding the foregoing, a Transfer to a Competitor, or an Affiliate of a
Competitor, of the Company shall not be a Permitted Transfer. For purposes of
this Agreement, "Family Group" means as to any Stockholder who is a natural
person his or her spouse, siblings, parents and descendants (whether natural or
adopted) and any trust solely for the benefit of such Stockholder or his or her
spouse, siblings, parents and/or descendants.

            (d) Any Affiliate of a Stockholder who receives any Shares shall
Transfer such Shares to the Stockholder from whom the Shares were originally
received or acquired within 5 days after ceasing to be an Affiliate of such
Stockholder.

            (e) The restrictions set forth in this Section 2(a) - (d) shall
continue with respect to each Share until the earlier of (i) the date on which
such Share has been transferred in a Public Sale or (ii) the consummation of a
Qualified Public Offering.

            (f) Each certificate evidencing Shares and each certificate issued
in exchange for or upon the transfer of any Shares (if such shares remain Shares
after such transfer) shall be stamped or otherwise imprinted with legends in
substantially the following form:

            "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A
            STOCKHOLDERS AGREEMENT DATED AS OF JUNE 27, 2001 AMONG PRA HOLDINGS,
            INC. (THE "COMPANY") AND CERTAIN OF THE COMPANY'S STOCKHOLDERS, AS
            AMENDED AND MODIFIED FROM TIME TO TIME. A COPY OF SUCH STOCKHOLDERS
            AGREEMENT SHALL BE FURNISHED WITHOUT CHARGE BY THE COMPANY TO THE
            HOLDER HEREOF UPON WRITTEN REQUEST.

            THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE NOT BEEN
            REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED (THE
            "SECURITIES ACT"), OR ANY STATE SECURITIES LAWS AND MAY NOT BE
            TRANSFERRED, SOLD OR OTHERWISE DISPOSED OF

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            EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION UNDER THE SECURITIES
            ACT OR PURSUANT TO AN OPINION OF COUNSEL, SATISFACTORY TO THE
            COMPANY, TO THE EFFECT THAT AN EXEMPTION FROM SUCH REGISTRATION IS
            AVAILABLE."

The Company shall imprint such legends on certificates evidencing Shares
outstanding as of the date hereof. The legends set forth above shall be removed
from the certificates evidencing any shares which cease to be Shares or which
are eligible for sale pursuant to Rule 144 (or any similar rule or rules then in
effect) of the Securities and Exchange Commission.

            (g) Following the Company's initial Public Offering and for so long
as the Company is subject to the reporting requirements under the Securities
Exchange Act of 1934, as amended, the Company shall, upon the reasonable written
request of a holder of Shares, supply to such Person or its prospective
transferees all information regarding the Company required to be delivered in
connection with a Transfer pursuant to Rule 144 (or any similar rule or rules
then in effect) of the Securities Act.

      3 "Bring-Along" Right.

            (a) If the Board and the holders of a majority of the shares of
Common Stock then outstanding approve a sale of the Company and the
consideration to be distributed to each BHC Holder (or its Affiliates) in
respect of such sale is consistent with the limitations set forth in clauses
(X), (Y) and (Z) of Section 3(b) below (each, an "Approved Sale"), each
Stockholder shall vote for, consent to and take all actions required in
connection with, and raise no objections to, such Approved Sale. If the Approved
Sale is structured as a (i) merger, consolidation or similar business
combination, each holder of Shares shall vote in favor of the merger,
consolidation or business combination and waive any dissenters' rights,
appraisal rights or similar rights in connection with such merger, consolidation
or similar business combination or (ii) sale of stock, each holder of Shares
shall agree to sell all of his, her or its Shares and rights to acquire Shares,
in each case on the same terms and conditions (including price) approved by the
Board and applicable to all holders of the Common Stock then outstanding subject
to Section 3(c) below, subject in each case to the last sentence of Section 3(b)
below. Each holder of Shares shall take all necessary or desirable actions in
connection with the consummation of the Approved Sale as requested by the
Company.

            (b) The obligations of the holders of Shares with respect to the
Approved Sale are subject to the satisfaction of the following conditions: (i)
upon the consummation of the Approved Sale, each Stockholder and each holder of
Shares (in his, her or its capacity as such) shall have the right to receive the
same terms, conditions and form of consideration with respect to such Shares
(and in the same proportion of the aggregate consideration with respect to such
Approved Sale that such holder would have received if the Shares constituted all
of the issued and outstanding capital stock of the Company and if such aggregate
consideration had been distributed by the Company in complete liquidation
pursuant to the rights and preferences set forth in the Company's Certificate of
Incorporation as in effect immediately prior to such Approved Sale); (ii) if any
holders of a class of Shares are given an option as to the form and amount of
consideration to be received, each holder of such class of Shares shall be given
the same option; and (iii) each holder of then currently exercisable rights to
acquire shares of a class

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of Shares shall be given an opportunity to either (A) exercise such rights prior
to the consummation of the Approved Sale and participate in such sale as a
holder of such exercised Shares or (B) upon the consummation of the Approved
Sale, receive in exchange for such rights consideration equal to the amount
determined by multiplying (1) the same amount of consideration per share of a
class of Shares received by holders of such class of Shares in connection with
the Approved Sale less the exercise price per share of such class of Shares of
such rights to acquire such class of Shares by (2) the number of shares of such
class of Shares represented by such rights held by such holder assuming such
rights were exercised as of the date of consummation of the Approved Sale;
provided, however, that if the purchaser in any Approved Sale desires to have
some or all Stockholders who are members of the Company's management retain or
rollover some or all of their Shares and/or desires to have the Genstar
Investors and their Affiliates and/or other specified stockholders of the
Company retain or rollover some or all of their Shares in order to qualify the
Approved Sale for recapitalization accounting, the foregoing provisions in (i),
(ii) and (iii) shall not apply to the extent of any such retention or rollover;
provided further, however, that no Stockholder shall be required by this
Agreement, without such Stockholder's written consent, to retain or rollover
some or all of their Shares, except in a merger in which all stockholders are
required to be treated equally with respect to such retention or rollover.
Notwithstanding anything in this Section 3 to the contrary, if, pursuant to a
proposed sale of the Company, any BHC Holder (together with any Affiliates)
would be obligated to receive with respect to its Shares any consideration other
than (X) cash, (Y) notes, or (Z) securities constituting 4.9% or less of the
Voting Securities of any class of the issuer thereof and 24.9% or less of the
total equity capital of the issuer thereof, then each Stockholder agrees to
cooperate with the Company in all reasonable respects, and the Company agrees to
take all reasonable actions, so that the BHC Holder (together with any
Affiliates) would hold, as a result of such proposed sale, consideration only of
the type set forth in clauses (X), (Y) and (Z) above, including to permit such
BHC Holder (and its Affiliates) to receive non-voting securities of the issuer
that are identical in all respects (other than voting) to the voting securities
that such BHC Holder (and its Affiliates) would otherwise receive and/or to
impose restrictions on the voting power of such securities.

            (c) Each Stockholder will bear, but shall not be required to bear
more than, his, her or its pro rata share (based upon the number of Shares to be
sold) of the costs of any sale of Shares pursuant to an Approved Sale to the
extent such costs are incurred for the benefit of all such holders of Shares and
are not otherwise paid by the Company or the acquiring party; provided that no
such Stockholder shall be required to make any such payment unless the Genstar
Investors are required to pay their pro rata share. Costs incurred by the
holders of Shares on their own behalf will not be considered costs of the
Approved Sale and shall be borne entirely by such holders. Each Stockholder
transferring Shares pursuant to an Approved Sale shall be obligated to join on a
pro rata basis (based on the number of Shares to be sold) in any indemnification
or other obligations that are part of the terms and conditions of the Approved
Sale (other than any such obligations that relate specifically to a particular
Stockholder, such as indemnification with respect to representations and
warranties given by a Stockholder regarding such Stockholder's title to and
ownership of Shares). Notwithstanding the foregoing, no Stockholder shall be
obligated in connection with any Approved Sale to agree to indemnify or hold
harmless the transferees in an amount in excess of the net proceeds paid to such
Stockholder in connection with the Approved Sale.

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      4 "Tag-Along" Right.

            (a) Subject to Section 5 hereof, in the event that the Genstar
Investors or their Affiliates (as defined in Section 2(c) hereof but, following
the consummation of an initial Public Offering, not including its limited
partners or non-managing members who received a pro rata distribution of
restricted securities from the Genstar Investors) (any of the above, the
"Transferring Holder") propose to effect a direct or indirect Transfer (other
than (i) a Permitted Transfer as defined in Section 2(c) hereof, (ii) a Transfer
pursuant to Section 3 hereof or (iii) a Transfer to the Company or the
Significant Holders pursuant to Section 5 hereof) of Shares, the Transferring
Holder shall promptly give written notice (the "Sale Notice") to the Company and
the other Stockholders at least 30 days prior to the closing of such Transfer.
The Sale Notice shall describe in reasonable detail the proposed Transfer
including, without limitation, the name of, and the number (by class) of Shares
to be purchased by, the transferee, the purchase price of each Share to be sold,
the number of shares the Transferring Holder proposes to Transfer, any other
material terms of the proposed Transfer and the date the proposed Transfer will
be consummated.

            (b) Each other Stockholder may elect to participate in the
contemplated Transfer by delivering irrevocable written notice to the
Transferring Holder setting forth the number of Shares such Stockholder desires
to sell in the contemplated Transfer within 10 days after receipt of the Sale
Notice. If any Stockholders have elected to participate in such Transfer (each,
a "Participant"), each such Participant shall be entitled to sell in the
contemplated Transfer, at the same price and on the same terms as the
Transferring Holder, a number of Shares equal to the product of (A) the quotient
determined by dividing the percentage of outstanding Shares owned by such
Participant by the aggregate percentage of outstanding Shares owned by the
Transferring Holder and all Participants and (B) the number of Shares to be sold
in the contemplated Transfer.

            (c) The Transferring Holder shall use commercially reasonable
efforts to obtain the agreement of the prospective transferee(s) to the
participation of the Participants in any contemplated Transfer, and the
Transferring Holder may not Transfer any of their respective Shares to the
prospective transferee(s) if the prospective transferee(s) declines to allow the
participation of the Participants in accordance with the foregoing formula.

            (d) Each Participant will bear its pro rata share (based upon the
number of shares sold) of the reasonable costs of any sale of Shares pursuant to
a sale subject to this Section 4 to the extent such costs are incurred for the
benefit of all selling Stockholders and are not otherwise paid by the Company or
the acquiring party; provided, that no such Participant shall be required to
make any such payment unless Genstar is required to pay its pro rata share.
Costs incurred by the Participants on their own behalf will not be considered
costs of the transaction hereunder and shall be borne entirely by such
Participants. Each Participant transferring Shares pursuant to this Section 4
shall be obligated to join on a pro rata basis (based on the number of Shares to
be sold) in any indemnification or other obligations that are part of the terms
and conditions of such Transfer (other than any such obligations that relate
specifically to a particular Participant, such as indemnification with respect
to representations and warranties given by a Stockholder regarding such
Stockholder's title to and ownership of Shares). Notwithstanding the foregoing,
no Participant shall be obligated in connection with any Transfer pursuant to
this

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Section 4 to agree to indemnify or hold harmless the transferees in an amount in
excess of the net proceeds paid to such Participant in connection with such
Transfer.

      5 Right of First Refusal.

            (a) Other than with respect to a Transfer pursuant to Section 3
hereof or a Permitted Transfer, if, at any time after the date of this Agreement
and prior to a Qualified Public Offering, any Stockholder receives a bona fide
offer to purchase any or all of his, her or its Shares (an "Offer") from a third
party (including the Company or another Stockholder) (an "Offeror") which the
Stockholder wishes to accept, such Stockholder shall cause such Offer to be
reduced to writing and shall notify the Company and each Significant Holder, in
writing of his, her or its wish to accept such Offer. The Stockholder's notice
shall contain an irrevocable offer to sell such Shares to the Company and the
Significant Holders (in the manner set forth below) at a purchase price equal to
the price contained in, and on the same terms and conditions of, such Offer, and
shall be accompanied by a true copy of such Offer (which shall identify the
Offeror thereof). First, at any time within 30 days after the date of the
receipt by the Company of the Stockholder's notice described above, the Company
may elect to purchase all or any portion of the Shares covered by the Offer
either (i) at the same price and on the same terms and conditions as the Offer
or (ii) if the Offer includes any consideration other than cash, then at the
sole option of the Company, at the equivalent all cash price, determined in good
faith by the Company's Board, by delivering written notice of such election to
the Stockholder and the other Significant Holders. If the Company notifies the
Significant Holders that it has not elected to purchase all of the Shares
covered by the Offer within such 30 day period or if the Company does not
provide any notice with respect to its election to purchase such Shares with
such 30 day period, each Significant Holder may elect to purchase his, her or
its "pro rata portion" (as defined below) of all or any remaining portion of the
Shares covered by the Offer at the same price and on the same terms and
conditions as the Offer by delivering written notice of such election to the
Stockholder at the principal office of the Company as soon as practical after
the delivery of the Offer notice, but in any event within 5 days after the
expiration of the Company's election. Failure to respond in writing within such
period shall be deemed an irrevocable waiver by such Significant Holder of such
Significant Holder's right to acquire its portion of the Shares. Each
Significant Holder shall have a right of over-allotment such that if any
Significant Holder fails to exercise its right to purchase its pro rata portion
of the Shares covered by the Offer, the other Significant Holders may purchase
his, her or its portion of the Shares not purchased within 5 days from the date
such non-purchasing Significant Holder fails to exercise its rights hereunder.
For purposes of this Section 5, pro rata portion shall mean the number of Shares
then owned by a Significant Holder divided by the number of Shares then owned by
all of the Significant Holders; provided that with respect to those Significant
Holders who are Management Investors the number of Shares to be used in the
calculation shall include only Assumed Options, Shares issuable upon Assumed
Options and Rollover Shares held by such Significant Holders.

            (b) If the Company and the Significant Holders have elected to
purchase any or all of such Shares pursuant to this Section 5, the closing of
such purchase shall occur within 30 days from the date the Company or the
Significant Holders, as applicable, have notified such Stockholder of his, her
or its election to purchase such Shares, at which time the Company or the
Significant Holders, as applicable, shall deliver a certified bank check or
checks in the appropriate amount to the Stockholder at the principal office of
the Company against delivery of

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certificates or other instruments representing the Shares so purchased,
appropriately endorsed by the Stockholder.

            (c) If at the end of the 40 day period during which the Company and
the Significant Holders may give notice to the Stockholder of his, her or its
election to purchase the Shares covered by the Offer, none of the Company or the
Significant Holders have elected to purchase all such Shares in the manner set
forth above, the Stockholder may during the succeeding 60 day period sell not
less than all of the Shares covered by the Offer which the Company or the
Significant Holders have not elected to purchase to the Offeror at a price and
on terms no less favorable to the Stockholder than those contained in the Offer.
No sale may be made to any Offeror unless such Offeror agrees in writing with
the Company to be bound by the provisions of this Agreement. Promptly after any
such sale to an Offeror, the Stockholder shall notify the Company and the
Significant Holders of the consummation thereof and shall furnish such evidence
of the completion and time of completion of such sale and of the terms thereof
as may reasonably be requested by the Company. If, at the end of the 60 day
period following the expiration of the 40 day period during which the Company or
the Significant Holders may elect to purchase such Shares, the Stockholder has
not completed the sale of such Shares to the Offeror as aforesaid, all the
restrictions on sale, transfer and assignment contained in this Agreement shall
again be in effect with respect to such Shares.

            (d) The rights and obligations granted by this Section 5 shall
terminate upon the consummation of a Qualified Public Offering.

            (e) Notwithstanding anything herein to the contrary, in the event
that the Genstar Investors or their Affiliates propose to effect a direct or
indirect Transfer of Shares to the Company at any time pursuant to this Section
5, Genstar shall notify the Significant Holders at least 30 days prior to the
proposed closing of such Transfer. Such notice shall describe in reasonable
detail the proposed Transfer as set forth in Section 5(a) and (b) above. Each
Significant Holder shall be entitled to sell its pro rata portion of shares to
the Company on the same terms and conditions as the Genstar Investors or their
Affiliates pursuant to the procedures set forth in this Section 5.

      6 Grant of Preemptive Rights.

            (a) If the Company issues New Securities to any Person (such Person,
an "Acquiring Person") at any time after the date hereof, then the Company
hereby grants each Stockholder and/or its respective Affiliates (collectively,
the "Preemptive Rights Holders") preemptive rights to purchase a pro rata
portion of such New Securities at the same price and on the same terms and
conditions offered to such Acquiring Person. In the event (and on each occasion)
that the Company shall decide to undertake an issuance of New Securities to an
Acquiring Person at any time after the date hereof, the Company will give all
Preemptive Rights Holders written notice (a "Preemptive Notice") of the
Company's decision, describing the type of New Securities and the terms upon
which the Company has decided to issue the New Securities (including, without
limitation, the expected timing of such issuance which will in no event exceed
60 days after the date of the Preemptive Notice).

            (b) Each of the Preemptive Rights Holders shall have 10 business
days from the date on which it receives a Preemptive Notice to agree to purchase
its pro rata portion of such

                                       10

<PAGE>

New Securities for the applicable price and upon the same terms specified in the
Preemptive Notice by giving written notice to the Company. Each Preemptive
Rights Holder shall have the option to purchase less than all of its pro rata
portion. If, in connection with such a proposed issuance of New Securities, any
Preemptive Rights Holder shall for any reason fail or refuse to give such
written notice to the Company within such 10 business day period, such
Preemptive Rights Holder shall, for all purposes of this Section 6, be deemed to
have refused (in that particular instance only) to purchase any of such New
Securities and to have waived (in that particular instance only) all of its
rights under this Section 6 to purchase any of such New Securities. Upon
expiration of the offering periods described in this Section 6, the Company
shall be entitled to sell such New Securities which the Preemptive Rights
Holders have elected not to purchase during the 120 days following such
expiration on terms and conditions no more favorable to the purchasers thereof
than those offered to the Preemptive Rights Holders in the Preemptive Notice.
Any New Securities offered or sold by the Company after such 120-day period must
be reoffered to the applicable Preemptive Rights Holders. The rights granted by
this Section 6 shall terminate upon the consummation of a Qualified Public
Offering.

            (c) Notwithstanding anything herein to the contrary, no Preemptive
Rights Holder has any preemptive rights with respect to any New Securities
issued in connection with (i) debt financing, except that if the Company issues
debt and equity securities together (i.e., as a "strip"), then such debt and
equity securities shall together be deemed to be New Securities, in which case
the Preemptive Rights Holders shall be entitled to purchase their pro rata
portion of both the debt and the equity securities being offered by the Company;
provided, however, that in such case, the Preemptive Rights Holder must elect to
purchase its pro rata portion of both the debt and the equity securities of the
Company issued in such financing, (ii) the exercise of Options, Warrants or
other rights or the conversion or exchange of securities of the Company, (iii)
the receipt of paid-in-kind dividends, provided that the underlying securities
were issued in compliance with this Section 6, (iv) a stock split, stock
dividend, stock distribution or recapitalization in which all similarly situated
Stockholders are treated in a similar manner, (v) issuances in any Public
Offering, (vi) issuances to the directors, officers or employees of the Company
or any Subsidiary of the Company pursuant to a benefit plan or similar
arrangement or as an inducement to hire a director, officer or employee of the
Company or any Subsidiary of the Company, provided that such issuances are
approved by the Board, (vi) issuances to customers, suppliers or lenders of the
Company, provided that such issuances are approved by the Board, or (vii)
issuances as consideration in connection with mergers, acquisitions of
securities or assets by the Company or its Subsidiaries or other business
combination transactions involving the Company or its Subsidiaries, provided
that such issuances are approved by the Board. As used in this Section 6, the
term "pro rata portion" with respect to a Preemptive Rights Holder shall mean
the aggregate number of New Securities to be issued multiplied by a fraction,
the numerator of which is the number of Shares held at such time by such
Preemptive Rights Holder and the denominator of which is the aggregate number of
Shares on a fully diluted, as converted, basis.

      7 Call Upon Termination of Management.

            (a) Subject to provisions to the contrary in outstanding stock
option or employment agreements between the Company and a Management Investor,
upon the death, disability, retirement or termination of employment (each a
"Call Event") of any Management Investor employed immediately prior to such Call
Event by the Company or any of the

                                       11

<PAGE>

Company's Subsidiaries, the Company or its designee shall, on terms and subject
to the conditions set forth in this Section 7, have the right (the "Employee
Call") at the option of the Company, to purchase all or any portion of the Call
Shares held by such Management Investor or transferred by such Management
Investor to a Person pursuant to a Permitted Transfer, by delivering written
notice to such Management Investor, such Management Investor's estate or such
transferee, within 30 days after the occurrence of the Call Event. The offering
price for the Call Shares offered pursuant to this Section 7 shall be equal to
the Fair Market Value of such Call Shares at such time. As used in this
Agreement, the "Fair Market Value" of any Shares (including Call Shares) shall
be as determined in good faith by the Board (without discount for lack of
marketability or minority interest). In the event the Company and any Management
Investor cannot mutually agree upon the Fair Market Value determination, the
Management Investor may, at its option, select an independent appraiser of
national reputation mutually agreed to by the Company and such Management
Investor to determine the Fair Market Value of such Call Shares at such time. If
the appraiser's valuation is less than 110% of the valuation determined by the
Board, the Fair Market Value shall be deemed to be the valuation determined by
the Board. In the event the two valuations differ by more than 10%, the Company
and the Management Investor shall choose an independent appraiser of national
reputation. If the Board and the Management Investor are unable to agree upon an
independent appraiser, each shall select an independent appraiser and those two
shall select a third independent appraiser. The independent appraiser shall
determine which of the Board's valuation and the Management Investor's valuation
is closest to such appraiser's opinion as to the Fair Market Value and the
valuation selected by the independent appraiser shall be deemed to be the Fair
Market Value. The fees and expenses of the independent appraiser shall be paid
by the party whose valuation is not selected.

            (b) If the Company shall elect to exercise the Employee Call in
accordance with this Section 7, the closing of the purchase by the Company shall
take place no later than 45 days after the exercise of the Employee Call, which
period, in the case of the death of a Management Investor, may at the Company's
election be extended to provide for probate of such Stockholder's estate. On the
date scheduled for such closing, the price for the Shares subject to the
Employee Call shall be paid in full to the Management Investor (or his or her
estate) holding such Shares (including, if applicable, such Shares held by any
transferee of such Management Investor) by the Company or its designee against
delivery of a certificate or certificates, as the case may be, representing the
purchased Shares in proper form for transfer. In connection with such closing,
such Management Investor (or his or her estate) and/or transferee (as the case
may be) shall warrant to the Company or its designee sole, good and marketable
title to the purchased Shares, free and clear of all claims, liens, charges,
encumbrances and security interests of any nature whatsoever except those under
this Agreement.

      8 Board of Directors.

            (a) From and after the date hereof and until the provisions of this
Section 8 cease to be effective pursuant to Section 8(d) below, each Stockholder
shall vote all of his, her or its Shares which are voting shares and any other
voting securities of the Company over which such Stockholder has voting control
and shall take all other necessary or desirable actions within his or her
control (whether in his, her or its capacity as a stockholder, director, member
of a board committee or officer of the Company or otherwise, and including,
without limitation, attendance at meetings in person or by proxy for purposes of
obtaining a quorum and execution

                                       12

<PAGE>

of written consents in lieu of meetings), and the Company shall take all
necessary or desirable actions within its control (including, without
limitation, calling special board and stockholder meetings), so that:

                  (i) the authorized number of directors on the Board to be
elected by the holders of Common Stock shall be at four or such higher number as
may be specified from time to time in the sole discretion of the holders of a
majority of the Genstar Investor Shares then outstanding;

                  (ii) such individuals designated by Genstar (the "Principal
Investor Directors") shall be elected to the Board; provided that Genstar may
authorize in writing one or more other Persons (each an "Authorized Person") to
designate one or more additional individuals to be elected to the Board on such
terms and conditions as Genstar shall determine in its sole discretion
(provided, that any such Authorized Person shall consent in writing to such
designation); provided further that Genstar shall provide prompt notice to each
Significant Holder upon election to the Board of any individuals designated by
Genstar.

                  (iii) the removal from the Board (with or without cause) of
any individual designated hereunder by Genstar shall be at Genstar's written
request (or the written request of an Authorized Person in the case of an
individual designated by such Authorized Person), but only upon such written
request and under no other circumstances; and

                  (iv) in the event that any individual designated hereunder by
Genstar ceases to serve as a member of the Board during his term of office, the
resulting vacancy on the Board shall be filled by an individual designated by
Genstar (or by an individual designated by an Authorized Person in the case
where the representative ceasing to serve as a member of the Board was
designated by such Authorized Person).

            (b) If Genstar (or an Authorized Person) fails to designate an
individual to fill a directorship pursuant to the terms of this Section 8, the
individual previously holding such directorship shall be elected to such
position, or if such individual fails or declines to serve, the directorship
shall be vacant until filled in accordance with this Section 8.

            (c) The provisions set forth in this Section 8 shall remain in
effect until the consummation of a Qualified Public Offering.

      9 "Piggyback" Registration Rights.

            (a) Subject to Section 9(c) hereof, if the Company files a
registration statement in connection with a contemplated Public Offering in
which a Holder (as defined in the Registration Rights Agreement) would have the
right under Section 4(a) of the Registration Rights Agreement to receive a
Piggyback Notice (as defined in the Registration Rights Agreement), each
Additional Investor, Management Investor and Warrantholder hereby shall have all
of the rights and privileges of the Registration Rights Agreement, including,
but not limited to, the rights set forth in Section 4 of the Registration Rights
Agreement, and the Company and each Additional Investor, Management Investor and
Warrantholder agrees to be

                                       13

<PAGE>

bound by all of the terms, conditions and obligations of the Registration Rights
Agreement, in each case as if such Additional Investor, Management Investor and
Warrantholder were a "Holder" (as defined in the Registration Rights Agreement)
and as if the Shares of Common Stock held by each Additional Investor,
Management Investor and Warrantholder under this Agreement were "Registrable
Securities" (as defined in the Registration Rights Agreement); provided,
however, that this Section 9(a) shall not give the Additional Investor,
Management Investor and Warrantholder any rights under Section 3 of the
Registration Rights Agreement to request registration of any Shares.

            (b) No Person may participate in any underwritten registration
hereunder unless such Person (i) agrees to sell such Person's securities on the
basis provided in any underwriting arrangements approved by the Persons entitled
to approve such arrangements and (ii) completes and executes all questionnaires,
powers of attorney, indemnities, underwriting agreements and other documents
required under the terms of such underwriting arrangements. Nothing in this
Section 9 shall be construed to create any additional rights regarding the
registration of shares of Common Stock otherwise than as set forth herein.

            (c) Each Stockholder agrees, if requested by the managing
underwriters in a Public Offering, not to sell, make any short sale of, grant
any option for the purchase of, or otherwise dispose of, securities of the
Company the same as or similar to those being registered, or any securities
convertible into or exchangeable or exercisable for such securities, in such
registration statement, including a sale pursuant to Rule 144 under the
Securities Act (except as part of such Public Offering), during the 7-day period
prior to, and during the 90-day period (or such longer period of up to 180 days
as may be required by such underwriter) beginning on, the effective date of any
registration statement (except as part of such registration) or the commencement
of the public distribution of securities, to the extent timely notified in
writing by the Company or the managing underwriters.

      10 Representations and Warranties.

            (a) Each Stockholder represents and warrants as to itself that (i)
such Stockholder is the record owner of the number of Shares set forth opposite
his, her or its name on the applicable Exhibit attached hereto, (ii) this
Agreement has been duly authorized, executed and delivered by such Stockholder
and constitutes the valid and binding obligation of such Stockholder,
enforceable in accordance with its terms subject to (A) the effect of
bankruptcy, insolvency, reorganization, moratorium, fraudulent conveyance,
fraudulent transfer, preferential transfer or distribution laws and other
similar laws now or hereafter in effect relating to or affecting the rights of
creditors generally; and (B) the effect of (x) general principles of equity,
including without limitation concepts of materiality, reasonableness, good faith
and fair dealing and the possible unavailability of specific performance or
injunctive relief, regardless of whether considered in a proceeding in equity or
at law and (y) the discretion of any court in which an action is brought, and
(iii) such Stockholder has not granted and is not a party to any proxy, voting
trust or other agreement which is inconsistent with, conflicts with or violates
any provision of this Agreement. No holder of Shares shall grant any proxy or
become party to any voting trust or other agreement which is inconsistent with,
conflicts with or violates any provision of this Agreement.

                                       14

<PAGE>

            (b) The Company represents and warrants that this Agreement has been
duly authorized, executed and delivered by the Company and constitutes the valid
and binding obligation of the Company, enforceable in accordance with its terms
subject to (i) the effect of bankruptcy, insolvency, reorganization, moratorium,
fraudulent conveyance, fraudulent transfer, preferential transfer or
distribution laws and other similar laws now or hereafter in effect relating to
or affecting the rights of creditors generally; and (ii) the effect of (A)
general principles of equity, including without limitation concepts of
materiality, reasonableness, good faith and fair dealing and the possible
unavailability of specific performance or injunctive relief, regardless of
whether considered in a proceeding in equity or at law and (B) the discretion of
any court in which an action is brought.

      11 Financial Reports. The Company will deliver the following reports to
each Significant Holder and to Squam Lake Investors V, L.P. (so long as it holds
10,000 Shares (as appropriately adjusted for stock splits, stock dividends, and
the like)); provided that the Company may withhold delivery of any such reports
from any Management Investor who is then employed by, or engaged as consultant
for, a Competitor, of an Affiliate of a Competitor, of the Company:

            (a) Quarterly Financials: As soon as practical and in any event
within 45 days after the end of each Fiscal Quarter, the consolidated balance
sheets of the Company and its Subsidiaries as at the end of such quarter and the
related consolidated statements of income, stockholders' equity and cash flows
of the Company and its Subsidiaries for such quarter and for the period from the
beginning of the then current Fiscal Year to the end of such Fiscal Quarter, all
in reasonable detail, prepared in accordance with generally accepted accounting
principles, and;

            (b) Year-End Financials: As soon as practical and in any event
within 90 days after the end of each Fiscal Year the consolidated balance sheets
of Company and its Subsidiaries as at the end of such Fiscal Year and the
related consolidated statements of income, stockholders' equity and cash flows
of Company and its Subsidiaries for such Fiscal Year, all in reasonable detail,
prepared in accordance with generally accepted accounting principles.

      12 Power of Attorney. In order to secure each Stockholder's obligation to
(a) vote his, her or its Shares and other voting securities of the Company in
accordance with the provisions of Section 8 hereof and (b) comply with the
requirements of Section 3 hereof and, as applicable, Section 7 hereof
(collectively, the "Stockholder Obligations"), each Stockholder hereby
irrevocably appoints Genstar as his, her or its true and lawful
attorney-in-fact, with full power of substitution, to (i) vote all of his, her
or its Shares and other voting securities of the Company for the election and/or
removal of directors and all such other matters as expressly provided for in
Sections 3 and 8 hereof and (ii) take all actions, and execute and deliver all
agreements, certificates or other documents, in each case necessary to implement
and give effect to the agreements set forth in Sections 3 and 7 hereof in the
name and for the benefit and obligation of such Stockholder; provided that
Genstar shall not exercise the irrevocable power of attorney granted to it
hereunder with respect to any Stockholder unless the Stockholder has not
complied with its Stockholder Obligations and Genstar has provided (A) 10 days'
prior written notice requesting such Stockholder to comply with its Stockholder
Obligations, and (B) a second written notice, which shall give another 3
business days' prior written notice requesting such Stockholder to comply with
its Stockholder Obligations, such second notice having been

                                       15

<PAGE>

delivered on or after the expiration of such 10 business day period. The power
of attorney granted by each Stockholder pursuant to this Section 12 is coupled
with an interest and is given to secure the performance of each Stockholder's
obligations under this Agreement. Such power of attorney is irrevocable, and
shall survive the death, incompetency, disability, bankruptcy or dissolution of
such Stockholder, and the subsequent holders of his, her or its Shares. The
power of attorney granted hereunder with respect to a particular provision of
this Agreement shall terminate concurrently with the termination of that
provision.

      13 Rights to Negotiate Repurchase Price.

            (a) Subject to compliance with Sections 5 and 13(b) hereof, this
Agreement shall not be deemed to restrict or prohibit the Company from
purchasing Shares or Options from any Stockholder (except the Genstar Investors
and their Affiliates), at any time, upon such terms and conditions, and for such
price, as may be mutually agreed upon between the parties, whether or not at the
time of such purchase circumstances exist which specifically grant the Company
the right to purchase, or the Stockholder the right to sell, Shares or which
specifically grant the Company the right to cancel Options.

            (b) No Stockholder shall approve of or participate in any direct or
indirect repurchase, redemption or retirement of any securities of the Company,
and the Company shall not directly or indirectly repurchase, redeem or retire
any securities of the Company if, after giving effect to, and as a result of,
such repurchase, redemption or retirement, any BHC Holder (together with any
Affiliates) would hold securities comprising more than 4.9% of the Voting
Securities of the Company or more than 24.9% of the total equity capital of the
Company; provided that if such a repurchase, redemption or retirement is
proposed, then each Stockholder agrees to cooperate with the Company in all
reasonable respects, and the Company agrees to take all reasonable actions, so
that such repurchase, redemption or retirement would not be consummated unless
such BHC Holder (together with any Affiliates) would not hold, as a result of
such repurchase, redemption or retirement, securities constituting more than
4.9% of the Voting Securities of any class of the issuer thereof or more than
24.9% of the total equity capital of the issuer thereof or consideration other
than cash, notes or securities, including to permit the BHC Holder (and its
Affiliates) to receive non-voting securities of the issuer that are identical in
all respects (other than voting) to the voting securities that such BHC Holder
(and its Affiliates) would otherwise receive and/or to impose restrictions on
the voting power of such securities.

      14 Recapitalizations, etc.

            (a) The provisions of this Agreement shall apply, to the full extent
set forth herein with respect to the Shares, Warrants and the Options, to any
and all shares of capital stock of the Company or any capital stock, partnership
units or any other security evidencing ownership interests in any successor or
assign of the Company (whether by merger, consolidation, sale of assets or
otherwise) which may be issued in respect of, in exchange for, or in
substitution of the Stock or the Options, by reason of any stock dividend,
split, reverse split, combination, recapitalization, liquidation,
reclassification, merger, consolidation or otherwise.

            (b) No Stockholder shall approve of or participate in, and the
Company shall not agree to, or undertake or participate in, any recapitalization
(including any stock dividend, split, reverse split, reclassification),
combination, merger, consolidation or other similar

                                       16

<PAGE>

transaction (other than an Approved Sale pursuant to Section 3 hereof) if, after
giving effect to, and as a result of such recapitalization, combination, merger,
consolidation or other similar transaction, any BHC Holder (together with any
Affiliates) would receive with respect to its Shares any consideration other
than (X) cash, (Y) notes or (Z) securities constituting 4.9% or less of the
Voting Securities of any class of the Company (or any other issuer resulting
from such transaction) and securities comprising 24.9% or less of the total
equity capital of the Company (or any other issuer resulting from such
transaction); provided that if such a transaction is proposed, then each
Stockholder agrees to cooperate with the Company in all reasonable respects, and
the Company agrees to take all reasonable actions, so that such BHC Holder
(together with any Affiliates) would not hold, as a result of such transaction,
securities constituting more than 4.9% of the Voting Securities of any class of
the issuer thereof or more than 24.9% of the total equity capital of the issuer
thereof or consideration other than cash, notes or securities, including to
permit the BHC Holder (and its Affiliates) to receive non-voting securities of
the issuer that are identical in all respects (other than voting) to the voting
securities that such BHC Holder (and its Affiliates) would otherwise receive
and/or to impose restrictions on the voting power of such securities.

            (c) The Company shall not make any distribution or dividend if,
after giving effect to, and as a result of such distribution or dividend, any
BHC Holder (together with any Affiliates) would hold more than 24.9% of the
total equity capital of the Company.

      15 Stockholder's Employment by the Company. Nothing contained in this
Agreement (a) obligates the Company or any Subsidiary of the Company to employ
any Stockholder in any capacity whatsoever or (b) prohibits or restricts the
Company (or any of its Subsidiaries) from terminating the employment, if any, of
any Stockholder at any time or for any reason whatsoever, with or without cause,
and each Stockholder hereby acknowledges and agrees that neither the Company nor
any other person has made any representations or promises whatsoever to such
Stockholder concerning such Stockholder's employment or continued employment by
the Company.

      16 Binding Effect. The provisions of this Agreement shall be binding upon
and accrue to the benefit of the parties hereto and their respective heirs,
legal representatives, successors and assigns. In the case of a transferee
permitted under Section 2(c) hereof, such Permitted Transferee shall be deemed
the Stockholder hereunder; provided, however, that no transferee (including
without limitation, transferees referred to in Section 2 hereof) shall derive
any rights under this Agreement unless and until such transferee has delivered
to the Company a valid undertaking to become bound by the terms of this
Agreement.

      17 Amendment. No provision of this Agreement may be amended, modified or
waived without the prior written consent of the Stockholders of more than a
majority of the Common Stock (on a fully diluted basis) held by such
Stockholders then outstanding; provided that no amendment or modification to, or
deletion of, this Section 17 shall be effective unless unanimously approved by
all Stockholders, and provided further that no amendment, modification or waiver
shall adversely affect the rights or obligations of any Stockholder (x)
contained in Sections 4, 5, 6, 7 and 9, (y) contained in any other provision of
this Agreement in a manner different from any other Stockholder, or (z)
specifically granted to such Stockholder but not to all other Stockholders, in
each case without such Stockholder's prior written consent. Notwithstanding the
foregoing, the addition of parties to this Agreement in accordance with its

                                       17

<PAGE>

terms shall not be deemed to be an amendment, modification or waiver requiring
the consent of any Stockholder.

      18 Governing Law. All issues and questions concerning the relative rights
of the Company and its stockholders and all other issues and questions
concerning the construction, validity, interpretation and enforceability of this
Agreement and the exhibits and schedules hereto shall be governed by, and
construed in accordance with, the laws of the State of Delaware, without giving
effect to any choice of law or conflict of law rules or provisions that would
cause the application of the laws of any jurisdiction other than the State of
Delaware. In furtherance of the foregoing, the internal law of the State of
Delaware shall control the interpretation and construction of this Agreement
(and all schedules and exhibits hereto), even though under that jurisdiction's
choice of law or conflict of law analysis, the substantive law of some other
jurisdiction would ordinarily apply.

      19 Miscellaneous. In this Agreement (i) all references to "dollars" or "$"
are to United States dollars and (ii) the word "or" is not exclusive. If any
provision of this Agreement shall be declared illegal, void or unenforceable by
any court of competent jurisdiction, the other provisions shall not be affected,
but shall remain in full force and effect.

      20 Notices. All notices and other communications provided for herein shall
be in writing and shall be deemed to have been duly given if delivered by hand
(whether by overnight courier or otherwise) or sent by registered or certified
mail, return receipt requested, postage prepaid, to the party to whom it is
directed:

                  (a) If to the Company, to it at the following addresses:

                                    PRA Holdings, Inc.
                                    8300 Greensboro Drive, Suite 400
                                    McLean, VA 22102
                                    Attention: Earle Martin
                                    Telecopy No.: (703) 748-5199  and

                                    c/o Genstar Capital, L.P.
                                    555 California Street, Suite 4850
                                    San Francisco, CA 94104
                                    Attention: Jean-Pierre L. Conte
                                    Telecopy No.: (415) 834-2383

                  (b) If to Genstar or Stargen, to it at the following address:

                                    Genstar Capital, L.P.
                                    555 California Street, Suite 4850
                                    San Francisco, CA 94104
                                    Attention: Jean-Pierre L. Conte
                                    Telecopy No.: (415) 834-2383

                  with a copy to:

                                       18

<PAGE>

                                    Latham & Watkins
                                    505 Montgomery Street, Suite 1900
                                    San Francisco, CA 94111
                                    Attn: Scott R. Haber
                                    Telecopy:  (415) 395-8095

                  (c) If to any Stockholder, to him, her or at its most recent
address as reflected in the Company's records,

or at such other address as the party shall have specified by notice in writing
to the other Parties in accordance with this Section 20.

                                       19

<PAGE>

      IN WITNESS WHEREOF, the Parties have executed this Stockholders Agreement
as of the date first above written.

COMPANY                           PRA HOLDINGS, INC.


                                  By: /s/ JEAN-PIERRE L. CONTE
                                     --------------------------------------
                                     Name: Jean-Pierre L. Conte
                                          ---------------------------------
                                     Its:  President
                                          ---------------------------------

GENSTAR INVESTORS                 GENSTAR CAPITAL PARTNERS III, L.P.

                                  By:  Genstar Capital III, L.P.
                                  Its: General Partner

                                       By:  Genstar III GP LLC
                                       Its: General Partner

                                       By: /s/ JEAN-PIERRE L. CONTE
                                          --------------------------------------
                                          Name: Jean-Pierre L. Conte
                                               ---------------------------------
                                          Its:  Managing Director
                                               ---------------------------------

                                  STARGEN III, L.P.

                                  By:  Genstar Capital III, L.P.
                                  Its: General Partner

                                       By:  Genstar III GP LLC
                                       Its: General Partner

                                       By: /s/ JEAN-PIERRE L. CONTE
                                          --------------------------------------
                                          Name: Jean-Pierre L. Conte
                                               ---------------------------------
                                          Its:  Managing Director
                                               ---------------------------------

                                  [Signatures Continued on Next Page]

                     [Stockholders Agreement signature page]

<PAGE>

ADDITIONAL INVESTORS:             CAPITAL D'AMERIQUE CDPQ INC.

                                  By: /s/ GHISLAIN GAUTHIER
                                     -------------------------------------------
                                      Name: Ghislain Gauthier
                                           -------------------------------------
                                      Its:  Vice President
                                           -------------------------------------

                                  By: /s/ CYRILLE VITTECOQ
                                     -------------------------------------------
                                      Name: Cyrille Vittecoq
                                           -------------------------------------
                                      Its:  Manager
                                           -------------------------------------

                                  SQUAM LAKE INVESTORS V, L.P.
                                  By: GPI, Inc., its Managing General Partner

                                  By: /s/ DAVID CURLEY
                                     -------------------------------------------
                                      Name: David Curley
                                           -------------------------------------
                                      Its:  Vice President
                                           -------------------------------------

                                  WABAN INVESTORS I, L.P.
                                  By: BG Investments, Inc., its Managing
                                      General Partner

                                  By: /s/ STUART K. MIN
                                     -------------------------------------------
                                      Name: Stuart K. Min
                                           -------------------------------------
                                      Its:  Vice President
                                           -------------------------------------

                                  SUNAPEE SECURITIES, INC.

                                  By: /s/ CHRISTOPHER QUINN
                                     -------------------------------------------
                                      Name: Christopher Quinn
                                           -------------------------------------
                                      Its:  Assistant Treasurer
                                           -------------------------------------

                                  WFC HOLDINGS CORPORATION

                                  By: /s/ GILBERT SHEN
                                     -------------------------------------------
                                      Name: Gilbert Shen
                                           -------------------------------------
                                      Its:  Attorney-in-fact
                                           -------------------------------------

                                  [Signatures Continued on Next Page]

                     [Stockholders Agreement signature page]

<PAGE>

                                  PARIBAS NORTH AMERICA, INC.

                                  By: /s/ GEORGE T. DEASON
                                     -------------------------------------------
                                      Name: George T. Deason
                                           -------------------------------------
                                      Its:  Vice President
                                           -------------------------------------

                                  THE TORONTO-DOMINION BANK

                                  By: /s/ I. BROIN
                                     -------------------------------------------
                                      Name: I. Broin
                                           -------------------------------------
                                      Its:  VP Administration
                                           -------------------------------------

                                  LANSING BROWN INVESTMENTS, LLC

                                  By: /s/ JOHN L. ZABRISKIE
                                     -------------------------------------------
                                      Name: John L. Zabriskie
                                           -------------------------------------
                                      Its:  President
                                           -------------------------------------

                                  [Signatures Continued on Next Page]

                     [Stockholders Agreement signature page]

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MANAGEMENT INVESTORS:             EARLE MARTIN

                                  /s/ EARLE MARTIN
                                  ----------------------------------------------

                                  DAVID DOCKHORN

                                  /s/ DAVID DOCKHORN
                                  ----------------------------------------------

                                  JOACHIM VOLLMAR

                                  /s/ JOACHIM VOLLMAR
                                  ----------------------------------------------

                                  PATRICK DONNELLY

                                  /s/ PATRICK DONNELLY
                                  ----------------------------------------------

                                  STEVEN DECHERNEY

                                  /s/ STEVEN DECHERNEY
                                  ----------------------------------------------

                                  JAMES POWERS

                                  /s/ JAMES POWERS
                                  ----------------------------------------------

                                  BRUCE TEPLITZKY

                                  /s/ BRUCE TEPLITZKY
                                  ----------------------------------------------

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                     [Stockholders Agreement signature page]

<PAGE>

MANAGEMENT INVESTORS:             WILLIAM WALSH

                                  /s/ WILLIAM WALSH
                                  -----------------------------------

                                  [Signatures Continued on Next Page]

                     [Stockholders Agreement signature page]

<PAGE>

WARRANTHOLDERS:                   CAPITAL D'AMERIQUE CDPQ INC.

                                  By: /s/ GHISLAIN GAUTHIER
                                      ------------------------
                                      Name: Ghislain Gauthier
                                      Its:  Vice President

                                  By: /s/ CYRILLE VITTECOQ
                                      ------------------------
                                      Name: Cyrille Vittecoq
                                      Its: Manager



                                  WFC HOLDINGS CORPORATION

                                  By: /s/ GILBERT SHEN
                                      -----------------------
                                      Name: Gilbert Shen
                                      Its: Attorney-in-fact

                     [Stockholders Agreement signature page]

<PAGE>

MANAGEMENT INVESTORS:             ERICH MOHR

                                  /s/ ERICH MOHR
                                  -------------------------------------------

                                  KEN NEWPORT

                                  /s/ KEN NEWPORT
                                  -------------------------------------------

                                  SHELLEY MOHR

                                  /s/ SHELLEY MOHR
                                  -------------------------------------------

                                  CHRISTINE NEWPORT

                                  /s/ CHRISTINE NEWPORT
                                  -------------------------------------------

                     [Stockholders Agreement signature page]