Exhibit 2.2

                                VOTING AGREEMENT

            THIS VOTING AGREEMENT (this "Agreement") is entered into this 19th
day of June, 2000, by and among PA CONSULTING GROUP, INC., a New Jersey
corporation ("Acquiror"), PA HOLDINGS, INC., a Delaware corporation and a
wholly-owned subsidiary of Acquiror ("Merger Sub"), and each other Person listed
on the signature page hereof who is a stockholder (each a "Stockholder" and
collectively, the "Stockholders") of HAGLER BAILLY, INC., a Delaware corporation
(the "Company").

            WHEREAS, the Stockholders own of record and beneficially shares of
common stock, par value $.01 per share of the Company ("Company Common Stock")
and desire to enter into this Agreement with respect to such shares of Company
Common Stock;

            WHEREAS, Acquiror, Merger Sub, PA Holdings Limited and the Company
have contemporaneously with the execution of this Agreement entered into an
Agreement and Plan of Merger (the "Merger Agreement"), dated as of the date
hereof, which provides, among other things, for the merger (the "Merger") of the
Merger Sub with and into the Company pursuant to the terms and conditions
thereof; capitalized terms used herein and not otherwise defined shall have the
meanings given to such terms as in the Merger Agreement; and

            WHEREAS, as an essential condition and inducement to Acquiror and
Merger Sub entering into the Merger Agreement, Acquiror has required that the
Stockholders agree, and the Stockholders have agreed, to enter into this
Agreement.

            NOW, THEREFORE, the parties hereto, in consideration of the
foregoing, the mutual covenants and agreements contained herein and in the
Merger Agreement and for other good and valuable consideration, the receipt and
sufficiency of which hereby are acknowledged, and intending to be legally bound
hereby, agree as follows:

      SECTION 1. Voting

            (a) Each Stockholder hereby agrees to appear, or to cause the holder
of record on any applicable record date (the "Record Holder") to appear, in
person or by proxy, for the purpose of obtaining a quorum at any annual or
special meeting of stockholders of the Company and at any adjournment thereof at
which matters relating to the Merger, Merger Agreement or any transaction
contemplated thereby are considered; and

            (b) Each Stockholder further agrees that, it shall vote, or cause
the Record Holder to vote, in person or by proxy all of the shares of Company
Common


Stock, and any other voting interests in the Company owned or hereafter acquired
beneficially or of record by such Stockholder:

                  (i) in favor of the Merger and the adoption of the Merger
Agreement and the transactions contemplated thereby (including any amendments or
modifications of the terms thereof approved by the board of directors of the
Company and by Acquiror) in connection with any meeting of, or solicitation of
consents from, the stockholders of the Company at which or in connection with
which the Merger and the Merger Agreement are submitted for the consideration
and vote of the stockholders of the Company;

                  (ii) against approval or adoption of resolutions which would
have the effect of preventing or materially delaying consummation of the Merger
or otherwise preventing or materially delaying the Company from performing its
obligations under the Merger Agreement; and

                  (iii) against any action which would constitute a material
breach of any provision of the Merger Agreement.

            To the extent inconsistent with the foregoing provisions of this
Section 1, each Stockholder revokes any and all previous proxies with respect to
shares of Company Common Stock owned beneficially or of record by such
Stockholder and agrees not to grant any proxy with respect to and any other
voting interests in the Company owned or hereafter acquired beneficially or of
record by such Stockholder.

      SECTION 2. Further Assurances

            Each Stockholder shall, at such Stockholder's own expense, perform
such further acts and execute such further documents and instruments as may
reasonably be required to vest in Acquiror the power to carry out and give
effect to the provisions of this Agreement. Without limiting the generality of
the foregoing, none of the parties hereto shall enter into any agreement or
arrangement (or alter, amend or terminate any existing agreement or arrangement)
or transaction if such action would materially impair or materially interfere
with the ability of any party to effectuate, carry out and comply with all of
the terms of this Agreement.

      SECTION 3. Representations and Warranties of Each Stockholder

            Each Stockholder hereby, severally and not jointly, represents and
warrants to Acquiror as follows:

            (a) Such Stockholder has the legal capacity and all other power and
authority necessary to enter into this Agreement, to perform the obligations


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hereunder and to consummate the transactions contemplated hereby. This Agreement
has been duly executed and delivered by such Stockholder and, assuming due
authorization, execution and delivery of this Agreement by Acquiror, Merger Sub
and the other parties hereto, constitutes a legal, valid and binding obligation
of such Stockholder, enforceable in accordance with its terms, except as such
enforceability may be limited by bankruptcy, insolvency, reorganization,
moratorium and other similar laws of general applicability relating to or
affecting creditor's rights generally and by the application of general
principles of equity.

            (b) The execution and delivery of this Agreement and the
consummation of the transactions herein contemplated will not to the knowledge
of such Stockholder (i) conflict with or violate any law, regulation, court
order, judgment or decree applicable to such Stockholder or by which the
property of such Stockholder is bound or affected, or (ii) conflict with or
result in any breach of or constitute a default under any contract or agreement
to which such Stockholder is a party or by which such Stockholder or such
Stockholder's property is bound or affected, which conflict, violation, breach
or default would materially impair or materially interfere with such
Stockholder's ability to perform its obligations under this Agreement.

            (c) The execution and delivery of this Agreement and the
consummation of the transactions contemplated hereby do not and will not require
any consent or other action by any Person under, any provision of any agreement,
contract or other instrument binding on such Stockholder.

            (d) There are no proxies, voting agreements or other similar
arrangements with respect to the shares of Company Common Stock owned by such
Stockholder, except for the voting agreement arising hereunder.

      SECTION 4. Specific Performance

            Each Stockholder acknowledges and agrees that there would be no
adequate remedy at law for Acquiror or Merger Sub if such Stockholder fails to
perform any of such Stockholder's obligations hereunder, and accordingly agrees
that Acquiror and Merger Sub, in addition to any other remedy to which they may
be entitled at law or in equity, shall be entitled to compel specific
performance of the obligations of such Stockholder under this Agreement in
accordance with the terms and conditions of this Agreement in any court of the
United States or any State thereof having jurisdiction. Each Stockholder hereby
waives any objection to the imposition of such relief or to the posting of a
bond in connection therewith.

      SECTION 5. Governing Law


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            This Agreement shall be governed by, and construed in accordance
with, the laws of the State of Delaware, regardless of the laws that might
otherwise govern under applicable principles of conflicts of law.

      SECTION 6. Parties in Interest

            This Agreement shall inure to the benefit of and shall be binding
upon the parties hereto and their respective heirs, legal representatives and
assigns. If any Stockholder shall at any time hereafter acquire ownership of, or
voting power with respect to, any additional shares of Company Common Stock or
any other voting interests in the Company in any manner, whether by the exercise
of any options or any securities or rights convertible into or exchangeable for
shares of Company Common Stock or any other voting interests in the Company, by
operation of law or otherwise, such shares or other interests shall be held
subject to all of the terms and provisions of this Agreement. Without limiting
the foregoing, each Stockholder specifically agrees that the obligations of such
Stockholder hereunder shall not be terminated by operation of law, whether by
death or incapacity of such Stockholder or otherwise.

      SECTION 7. Amendment

            This Agreement shall not be amended, altered or modified except by
an instrument in writing duly executed and delivered on behalf of each of the
parties hereto.

      SECTION 8. Severability

            If any term or other provision of this Agreement is invalid, illegal
or incapable of being enforced by any rule of law, or public policy, all other
conditions and provisions of this Agreement shall nevertheless remain in full
force and effect. Upon such determination that any term or other provision is
invalid, illegal or incapable of being enforced, the parties hereto shall
negotiate in good faith to modify this Agreement so as to effect the original
intent of the parties as closely as possible to the fullest extent permitted by
applicable law in a mutually acceptable manner in order that the terms of this
Agreement remain as originally contemplated to the fullest extent possible.

      SECTION 9. Waiver

            Except as provided in this Agreement, no action taken pursuant to
this Agreement, including without limitation any investigation by or on behalf
of any party, shall be deemed to constitute a waiver by the party taking such
action of compliance with any representations, warranties, covenants or
agreements contained in this Agreement. The waiver by any party hereto of a
breach of any


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provision hereunder shall not operate or be construed as a wavier of any prior
or subsequent breach of the same or any other provision hereunder.

      SECTION 10. Notices

            All notices and other communications given or made pursuant hereto
shall be in writing and shall be deemed to have been duly given or made as of
the date delivered, mailed or transmitted, and shall be effective upon receipt,
if delivered personally, mailed by registered or certified mail (postage
prepaid, return receipt requested) to the parties at the following addresses (or
at such other address for a party as shall be specified by like changes of
address) or sent by electronic transmission to the telecopier number specified
below:

            If to a Stockholder:

            c/o Hagler Bailly, Inc.
            1530 Wilson Boulevard, Suite 400
            Arlington, VA 22209

            with a copy (which shall not constitute notice) to:

            Hogan & Hartson L.L.P.
            8300 Greensboro Drive
            Suite 1100
            McLean, VA 22102
            Telecopier No.: (703) 610-6200
            Attention: Richard T. Horan, Jr., Esq.

            If to Acquiror or Merger Sub:

            PA Consulting Group, Inc.
            c/o PA Consulting Group
            123 Buckingham Palace Road
            London SW1W 9SR
            England
            Telecopier No.: 44-1-207-333-5112
            Attention: Nick Hayes


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            with a copy (which shall not constitute notice) to:

            Loeb & Loeb LLP
            345 Park Avenue
            New York, New York 10154
            Telecopier No.: (212) 407-4990
            Attention: Stanley M. Johnson, Esq.

      SECTION 11. Entire Agreement; Assignment

            This Agreement (a) constitutes the entire agreement among the
parties hereto pertaining to the subject matter hereof and supersedes all prior
agreements, understandings, negotiations and discussions, whether oral or
written, of the parties and (b) shall not be assigned by operation of law or
otherwise, except that this Agreement shall be binding upon each Stockholder and
each Stockholder's successors and assigns, and the heirs, executors and
administrators of such Stockholder.

      SECTION 12. Headings

            Section headings are included solely for convenience and are not
considered to be part of this Agreement and are not intended to be an accurate
description of the contents thereof.

      SECTION 13. Counterparts

            This Agreement may be executed and delivered in one or more
counterparts, and by the different parties hereto in separate counterparts, each
of which when executed and delivered shall be deemed to be an original but all
of which taken together shall constitute one and the same agreement.

      SECTION 14. Expenses

            All costs and expenses incurred in connection with the transactions
contemplated by this Agreement shall be paid by the party incurring such costs
and expenses.

      SECTION 15. Termination

            This Agreement and all of the parties' rights and obligations
hereunder shall terminate on the earlier to occur of (a) the date on which the


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Merger Agreement is terminated pursuant to the provisions thereof, or (b) the
Effective Time as defined in the Merger Agreement (the "Termination Date").

      SECTION 16. Officers and Directors

            No person who is or becomes (during the term hereof) a director or
officer of the Company makes any agreement or understanding herein in his or her
capacity as such director or officer, and nothing herein will limit or affect,
or give rise to any liability to any of such Stockholders by virtue of, any
actions taken by any Stockholder in his or her capacity as an officer or
director of the Company in exercising its rights under the Merger Agreement.

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            IN WITNESS WHEREOF, the parties hereto have duly executed and
delivered this Voting Agreement, or have caused this Voting Agreement to be
executed and delivered on their behalf, as of the date first above written.


                                        PA CONSULTING GROUP, INC.

                                        By: /s/  Nick Hayes
                                           -------------------------------------
                                           Name:  Nick Hayes
                                           Title: Director


                                        PA HOLDINGS, INC.

                                        By: /s/  Nick Hayes
                                           -------------------------------------
                                           Name:  Nick Hayes
                                           Title: Director


                                        STOCKHOLDERS

                                        /s/ Henri-Claude A. Bailly
                                        ----------------------------------------
                                        Henri-Claude A. Bailly

                                        /s/ Jasjeet S. Cheema
                                        ----------------------------------------
                                        Jasjeet S. Cheema

                                        /s/ Robert W. Fri
                                        ----------------------------------------
                                        Robert W. Fri

                                        /s/ Richard H. O'Toole
                                        ----------------------------------------
                                        Richard H. O'Toole

                                        /s/ Howard W. Pifer III
                                        ----------------------------------------
                                        Howard W. Pifer III


                                        /s/ Fred M. Schriever
                                        ----------------------------------------
                                        Fred M. Schriever

                                        /s/ Alain M. Streicher
                                        ----------------------------------------
                                        Alain M. Streicher

                                        /s/ James Speyer
                                        ----------------------------------------
                                        James Speyer

                                        /s/ Geoffrey W. Bobsin
                                        ----------------------------------------
                                        Geoffrey W. Bobsin

                                        /s/ Roger W. Gale
                                        ----------------------------------------
                                        Roger W. Gale

                                        /s/ Stephen V.R. Whitman
                                        ----------------------------------------
                                        Stephen V.R. Whitman