<PAGE>
                                                                    EXHIBIT 10.1


                   FIFTH AMENDMENT AND LIMITED WAIVER TO THE
                   -----------------------------------------
                     AMENDED AND RESTATED CREDIT AGREEMENT
                     -------------------------------------

     THIS FIFTH AMENDMENT AND LIMITED WAIVER TO THE AMENDED AND RESTATED CREDIT
AGREEMENT (this "Amendment"), dated effective as of October 12, 2000, is among
                 ---------
RENAISSANCE WORLDWIDE, INC. ("Borrower"), a Massachusetts corporation, each of
                              --------
the banks or other lending institutions which is a party hereto (individually,
each a "Lender", and collectively the "Lenders") and BANK OF AMERICA, N.A., as
        ------                         -------
administrative agent for the Lenders (in such capacity, the "Administrative
                                                             --------------
Agent").
-----

                                   RECITALS:

     Borrower, the Administrative Agent and the Lenders have entered into that
certain Amended and Restated Credit Agreement dated as of July 15, 1999 (as
amended, restated, or modified from time to time, the "Credit Agreement").
                                                       ----------------
Borrower has requested that certain provisions of the Credit Agreement be
amended and/or waived in certain respects, and Administrative Agent and the
Lenders are willing to comply with such request as set forth herein.

     NOW, THEREFORE, BE IT RESOLVED, THAT, in consideration of the premises
herein contained and other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto hereby agree as
follows:


                                   ARTICLE 1

                                  Definitions
                                  -----------

     Section 1.1  Definitions.  Capitalized terms used in this Amendment, to the
                  -----------
extent not otherwise defined herein, shall have the same meanings as in the
Credit Agreement, as amended hereby.


                                   ARTICLE 2

                                Fifth Amendment
                                ---------------

     Section 2.1  Addition of Definition.  Section 1.1 of the Credit Agreement
                  ----------------------   -----------
is hereby amended by adding thereto in proper alphabetical order the definitions
of "Fifth Amendment", "The Hunter Group Dispositions" and "The Hunter Group
Stock Purchase Agreement", each to read in their entirety as follows:

          "Fifth Amendment" means that certain Fifth Amendment and Limited
           ---------------
     Waiver to the Amended and Restated Credit Agreement dated effective as of
     October 12, 2000 among Borrower, the Administrative Agent and the Lenders.
<PAGE>

          "The Hunter Group Dispositions" means, in aggregate, the dispositions
           -----------------------------
     of The Hunter Group, Inc., a Maryland corporation, Renaissance Worldwide
     Consulting Private Limited, an India corporation, and each of their
     respective Subsidiaries and certain related Property, all as more fully
     described in The Hunter Group Stock Purchase Agreement, to Cedar USA
     Holdings, Inc., a Delaware corporation, on or prior to October 27, 2000 for
     aggregate Net Proceeds of no less than Sixty-Five Million Dollars
     ($65,000,000).

          "The Hunter Group Stock Purchase Agreement" means that certain Stock
           -----------------------------------------
     Purchase Agreement, dated as of September 20, 2000, among Cedar USA
     Holdings, Inc., a Delaware corporation, Cedar Group Plc, a United Kingdom
     corporation, and Borrower, a final copy of which as executed has been
     delivered to the Administrative Agent.

     Section 2.2  Amendment to Definition of Revolving Commitment.  The final
                  -----------------------------------------------
sentence of the definition of "Revolving Commitment" appearing in Section 1.1 of
                                                                  -----------
the Credit Agreement is hereby amended to read in its entirety as follows:

     The aggregate amount of all the Revolving Commitments as of the effective
     date of the Fifth Amendment equals Sixty-Five Million Dollars
     ($65,000,000).

     Section 2.3  Amendment to Schedule 1.1.  Schedule 1.1 of the Credit
                  -------------------------   ------------
Agreement is hereby amended and restated to read in its entirety as set forth on
Exhibit "A" to this Amendment.
-----------

     Section 2.4  Amendment to Section 2.7.  Clause (c) of Section 2.7 of the
                  ------------------------   ----------    -----------
Credit Agreement is hereby amended by deleting the penultimate sentence thereof
in its entirety.

     Section 2.5  Amendment to Section 4.2.  Section 4.2 of the Credit Agreement
                  ------------------------   -----------
is hereby amended by adding the following sentence to end thereof to read in its
entirety as follows:

     Notwithstanding anything to contrary contained herein, upon consummation of
     The Hunter Group Dispositions, delivery to the Administrative Agent of the
     L/C Cash Collateral (as such term is defined in Section 11.8) and
                                                     ------------
     prepayment by Borrower of the Loans in full, all as set forth in clause
                                                                      ------
     (vii) of Section 11.8 of this Agreement, the L/C Fee Rate shall
     -----    ------------
     automatically be adjusted to be one-half of one percent (0.50%) per annum
     and the applicable fee (as calculated as set forth in, and as required to
     be paid by, Section 2.7(c)) shall be paid to the Administrative Agent
                 --------------
     solely for the account of the Issuing Bank (as such term is defined in
     Section 11.8).
     ------------

     Section 2.6  Amendments to Section 11.8.  Section 11.8 of the Credit
                  --------------------------   ------------
Agreement is hereby amended by changing the word "and" at the end of clause (v)
                                                                     ----------
thereof to a comma, by changing the period at the end of clause (vi) to the word
                                                         -----------
"and" and by adding thereafter the following clause (vii) to read in its
                                             ------------
entirety as follows:
<PAGE>

     (vii) The Hunter Group Dispositions; provided, however, that The Hunter
                                          --------  -------
     Group Dispositions are permitted only on the conditions that,
     contemporaneously with or prior to the closing of such dispositions, the
     Net Proceeds thereof be applied in amounts necessary for Borrower to (A)
     pledge to the Administrative Agent as security for the Reimbursement
     Obligations of the Issuing Bank (as defined below), pursuant to agreements
     in form and substance satisfactory to the Administrative Agent, an amount
     in immediately available funds equal to the then outstanding Letter of
     Credit Liabilities arising in connection with the Letters of Credit
     identified on Exhibit "B" to the Fifth Amendment (as used only in this
                   -----------
     Section 11.8, the "Current L/Cs"), such funds to be held in a cash
     ------------       ------------
     collateral account by the Administrative Agent for the benefit of the
     Issuing Bank without any right of withdrawal by Borrower (as used only in
     this Section 11.8, the "L/C Cash Collateral"), such account to bear
          ------------       -------------------
     interest at a standard and customary rate for time deposits, and (B) prepay
     the Loans in full.

          The prepayment of the Loans in full as set forth in clause (vii) shall
                                                              ------------
     ipso facto constitute the permanent and irrevocable termination of all
     Commitments of the Lenders under the Loan Documents other than the
     Reimbursement Obligations of Bank of America in its capacity as the issuer
     of each of the Current L/Cs (as used only in this Section 11.8, in such
                                                       ------------
     capacity the "Issuing Bank").  Contemporaneously with the receipt by the
                   ------------
     Administrative Agent of the L/C Cash Collateral and the prepayment of the
     Loans in full as set forth in clause (vii), the Liens of the Administrative
                                   ------------
     Agent and the Lenders against all Collateral other than the Liens of the
     Administrative Agent (for the benefit of the Issuing Bank) in the L/C Cash
     Collateral shall be released.  At any time during which the Current L/Cs
     are outstanding, all provisions of the Loan Documents relating to the L/C
     Cash Collateral, the Current L/Cs, the Reimbursement Obligations of the
     Issuing Bank, and the outstanding Letter of Credit Liabilities arising in
     connection with the Current L/Cs shall remain in full force and effect as
     between the Loan Parties, the Administrative Agent and the Issuing Bank.

          Upon return of the Current L/Cs to the Issuing Bank and upon delivery
     to the Issuing Bank of any other documentation reasonably requested by the
     Issuing Bank evidencing termination of the Letter of Credit Liabilities
     related thereto, the Liens of the Administrative Agent (for the benefit of
     the Issuing Bank) in the L/C Cash Collateral shall be released and all L/C
     Cash Collateral remaining after payment of any Reimbursement Obligations
     (if any) of the Issuing Bank shall be returned to Borrower.  At such time,
     all remaining Commitments of the Administrative Agent, Bank of America and
     the Issuing Bank shall permanently and irrevocably terminate.

          Notwithstanding any of the foregoing, all provisions of the Loan
     Documents which by their terms survive prepayment of the Loans and/or
     termination of the Commitments shall remain in full force and effect.
<PAGE>

                                   ARTICLE 3

                                Limited Waiver
                                --------------

     Section 3.1    Waiver.
                    ------

          (a)       The Borrower's failure to timely deliver the monthly
     financial statements and Compliance Certificate required, respectively, by
     subsections 10.1(b) and (c) of the Credit Agreement is hereby waived for
     -------------------     ---
     the calendar months ended July, 2000 and August, 2000.

          (b)       The Borrower's failure to, and failure to cause each
     Domestic Subsidiary of Borrower created or acquired prior to the date of
     this Amendment to, execute and deliver to the Administrative Agent all
     documentation necessary to comply with Section 7.3 and subsection 10.10(b)
                                            -----------     -------------------
     of the Credit Agreement is hereby temporarily waived (and only temporarily
     waived during the period set forth herein but not thereafter) from the date
     hereof to and until October 27, 2000.

     Section 3.2    Limitation of Waiver.  The waivers granted in Section 3.1 of
                    --------------------                          -----------
this Amendment shall be limited strictly as written and shall not be deemed to
constitute a waiver of, or any consent to noncompliance with, any term or
provision of any Loan Document except as expressly set forth herein.  Further,
the waivers granted in Section 3.1 of this Amendment shall not constitute a
                       -----------
waiver of any other Default arising as a result of the violation of any other
term or provision of any Loan Document, or a waiver of any rights or remedies
arising as a result of any such other Defaults.


                                   ARTICLE 4

                                  Conditions
                                  ----------

     Section 4.1    Conditions Precedent.  The effectiveness of this Amendment
                    --------------------
is subject to the satisfaction of the following conditions precedent:

          (a)       The representations and warranties contained herein and in
     all other Loan Documents, as amended hereby, shall be true and correct in
     all material respects as of the date hereof as if made on the date hereof,
     except for such representations and warranties limited by their terms to a
     specific date.

          (b)       After giving effect to Articles 2 and 3 hereof, no Default
                                           ----------     -
     or Event of Default shall have occurred and be continuing.

          (c)       Borrower shall have delivered to the Administrative Agent an
     executed original copy of this Amendment.
<PAGE>

          (d)       Borrower shall have paid to the Administrative Agent and
     each Lender all fees, costs and expenses owed to and/or incurred by each of
     the Administrative Agent and each such Lender arising in connection with
     this Amendment, including, without limitation, the reasonable fees, costs
     and expenses of the Administrative Agent's legal counsel, Jenkens &
     Gilchrist, a Professional Corporation.

          (e)       All proceedings taken in connection with the transactions
     contemplated by this Amendment and all documentation and other legal
     matters incident thereto shall be satisfactory to (i) the Administrative
     Agent, (ii) the Required Lenders and (iii) the Administrative Agent's legal
     counsel, Jenkens & Gilchrist, a Professional Corporation.


                                   ARTICLE 5

                 Ratifications, Representations and Warranties
                 ---------------------------------------------

     Section 5.1    Ratifications.  The terms and provisions set forth in this
                    -------------
Amendment shall modify and supersede all inconsistent terms and provisions set
forth in the Credit Agreement and, except as expressly modified and superseded
by this Amendment, the terms and provisions of the Credit Agreement and the
other Loan Documents are ratified and confirmed and shall continue in full force
and effect.  Borrower, the Administrative Agent and the Lenders agree that the
Credit Agreement as amended hereby and the other Loan Documents shall continue
to be legal, valid, binding and enforceable in accordance with their respective
terms.

     Section 5.2    Representations and Warranties.  Borrower hereby represents
                    ------------------------------
and warrants to the Administrative Agent and the Lenders that (i) the execution,
delivery and performance of this Amendment and any and all other Loan Documents
executed and/or delivered in connection herewith have been authorized by all
requisite action on the part of Borrower and will not violate the articles of
incorporation or bylaws of Borrower; (ii) the representations and warranties
contained in the Credit Agreement, as amended hereby, and any other Loan
Document are true and correct on and as of the date hereof as though made on and
as of the date hereof (except to the extent that such representations and
warranties were expressly, in the Credit Agreement, made only in reference to a
specific date); (iii) after giving effect to this Amendment, no Default or Event
of Default has occurred and is continuing; and (iv) Borrower is in full
compliance with all covenants and agreements contained in the Credit Agreement,
as amended hereby, and the other Loan Documents.



                                   ARTICLE 6

                                 Miscellaneous
                                 -------------
<PAGE>

     Section 6.1  Survival of Representations and Warranties.  All
                  ------------------------------------------
representations and warranties made in this Amendment or any other Loan Document
including any Loan Document furnished in connection with this Amendment shall
survive the execution and delivery of this Amendment and the other Loan
Documents, and no investigation by the Administrative Agent or any Lender shall
affect the representations and warranties or the right of the Administrative
Agent or any Lender to rely upon them.

     Section 6.2  Reference to Credit Agreement.  Each of the Loan Documents,
                  -----------------------------
including the Credit Agreement and any and all other agreements, documents, or
instruments now or hereafter executed and delivered pursuant to the terms hereof
or pursuant to the terms of the Credit Agreement as amended hereby, are hereby
amended so that any reference in such Loan Documents to the Credit Agreement
shall mean a reference to the Credit Agreement as amended hereby.

     Section 6.3  Severability.  Any provision of this Amendment held by a court
                  ------------
of competent jurisdiction to be invalid or unenforceable shall not impair or
invalidate the remainder of this Amendment and the effect thereof shall be
confined to the provision so held to be invalid or unenforceable.

     Section 6.4  Applicable Law.  THIS AMENDMENT SHALL BE GOVERNED BY AND
                  --------------
CONSTRUED IN ACCORDANCE WITH THE LAWS OF THE COMMONWEALTH OF MASSACHUSETTS AND
THE APPLICABLE LAWS OF THE UNITED STATES OF AMERICA.

     Section 6.5  Successors and Assigns.  This Amendment is binding upon and
                  ----------------------
shall inure to the benefit of the Administrative Agent, the Lenders, and
Borrower and their respective successors and assigns, except Borrower may not
assign or transfer any of its rights or obligations hereunder without the prior
written consent of all the Lenders.

     Section 6.6  Counterparts.  This Amendment may be executed in one or more
                  ------------
counterparts, and on telecopy counterparts each of which when so executed shall
be deemed to be an original, but all of which when taken together shall
constitute one and the same agreement.

     Section 6.7  Effect of Amendment.  No consent or waiver, express or
                  -------------------
implied, by the Administrative Agent or any Lender to or for any breach of or
deviation from any covenant, condition or duty by Borrower or any Loan Party
shall be deemed a consent or waiver to or of any other breach of the same or any
other covenant, condition or duty.

     Section 6.8  Headings.  The headings, captions, and arrangements used in
                  --------
this Amendment are for convenience only and shall not affect the interpretation
of this Amendment.
<PAGE>

     Section 6.9  ENTIRE AGREEMENT.  THIS AMENDMENT AND ALL OTHER INSTRUMENTS,
                  ----------------
DOCUMENTS AND AGREEMENTS EXECUTED AND DELIVERED IN CONNECTION WITH THIS
AMENDMENT EMBODY THE FINAL, ENTIRE AGREEMENT AMONG THE PARTIES HERETO AND
SUPERSEDE ANY AND ALL PRIOR COMMITMENTS, AGREEMENTS, REPRESENTATIONS AND
UNDERSTANDINGS, WHETHER WRITTEN OR ORAL, RELATING TO THIS AMENDMENT, AND MAY NOT
BE CONTRADICTED OR VARIED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT
ORAL AGREEMENTS OR DISCUSSIONS OF THE PARTIES HERETO.  THERE ARE NO ORAL
AGREEMENTS AMONG THE PARTIES HERETO.

                  [remainder of page intentionally left blank]
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have executed and delivered this
Amendment effective as of the date first written above.

                                        BORROWER:
                                        --------

                                        RENAISSANCE WORLDWIDE, INC.


                                        By:     /s/ Joseph F. Pesce
                                           -------------------------------------
                                        Name:   Joseph F. Pesce
                                             -----------------------------------
                                        Title:  Chief Financial Officer
                                              ----------------------------------


                                        LENDERS:
                                        -------

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

                                        By:     /s/ Fred L. Thorne
                                           -------------------------------------
                                        Name:   Fred L. Thorne
                                             -----------------------------------
                                        Title:  Managing Director
                                              ----------------------------------

                                        GMAC COMMERCIAL CREDIT LLC (formerly BNY
                                        Factoring LLC),
                                        as the Syndication Agent and as a Lender

                                        By:_____________________________________
                                        Name:___________________________________
                                        Title:__________________________________

                                        CITIZENS BANK OF MASSACHUSETTS

                                        By:_____________________________________
                                        Name:___________________________________
                                        Title:__________________________________

                                        THE CIT GROUP / BUSINESS CREDIT, INC.

                                        By:_____________________________________
                                        Name:___________________________________
                                        Title:__________________________________
<PAGE>

                                        DEBIS FINANCIAL SERVICES, INC.

                                        By:    /s/ James Vandervalk
                                           -------------------------------------
                                        Name:  James Vandervalk
                                             -----------------------------------
                                        Title: President - ABL Division
                                              ----------------------------------

                                        FINOVA CAPITAL CORPORATION

                                        By:    /s/ Bruce Mettel
                                           -------------------------------------
                                        Name:  Bruce Mettel
                                             -----------------------------------
                                        Title: Vice President
                                              ----------------------------------

                                        NATIONAL BANK OF CANADA

By:    /s/ Leonard J. Pellecchia        By:    /s/ A. Keith Broyles
   ---------------------------------       -------------------------------------
Name:  Leonard J. Pellecchia            Name:  A. Keith Broyles
     -------------------------------         -----------------------------------
Title: Vice President                   Title: Vice President & Manager
      ------------------------------          ----------------------------------

                                        PNC BUSINESS CREDIT

                                        By:    /s/ John W. Speiser
                                           -------------------------------------
                                        Name:  John W. Speiser
                                             -----------------------------------
                                        Title: Vice President
                                              ----------------------------------

                                        WEBSTER BANK

                                        By:    /s/ William H. Creaser
                                           -------------------------------------
                                        Name:  William H. Creaser
                                             -----------------------------------
                                        Title: Vice President
                                              ----------------------------------
<PAGE>

          REAFFIRMATION OF GUARANTY AND PLEDGE AND SECURITY AGREEMENT
          -----------------------------------------------------------

     Each of the undersigned hereby (i) consents to the execution and delivery
of the Fifth Amendment and Limited Waiver to the Amended and Restated Credit
Agreement to which this Reaffirmation of Guaranty and Pledge and Security
Agreement is attached (the "Amendment") by the parties thereto, (ii) agrees that
                            ---------
the Amendment shall not limit or diminish the obligations of each of the
undersigned under that certain Subsidiary Guaranty dated as of July 15, 1999 (as
amended, the "Guaranty"), or under that certain Pledge and Security Agreement
              --------
dated as of July 15, 1999 (as amended, the "Pledge and Security Agreement"),
                                            -----------------------------
executed or joined in by each of the undersigned and delivered to the
Administrative Agent, (iii) reaffirms its obligations under each of the Guaranty
and the Pledge and Security Agreement, and (iv) agrees that each of the Guaranty
and the Pledge and Security Agreement remains in full force and effect and is
hereby ratified and confirmed.

Dated effective as of October 12, 2000.


                                        THE HUNTER GROUP, INC.
                                        THE HUNTER GROUP INTERNATIONAL, INC.
                                        THE MANAGEMENT DECISIONS GROUP, INC.
                                        NEOGLYPHICS MEDIA CORPORATION
                                        RENAISSANCE GOVERNMENT SOLUTIONS, INC.
                                        RENAISSANCE WORLDWIDE INTERNATIONAL
                                             HOLDINGS, INC.
                                        RENAISSANCE WORLDWIDE IT CONSULTING
                                             SERVICES, INC.
                                        STERLING INFORMATION GROUP, INC.
                                        TRI SECURITIES CORP.

                                        By:    /s/ Joseph F. Pesce
                                           -------------------------------------
                                        Name:  Joseph F. Pesce
                                             -----------------------------------
                                        Title: Vice President for each of the
                                               foregoing
<PAGE>

                                        ARI NATIONAL COMPANY

                                        By:    /s/ Joseph F. Pesce
                                           -------------------------------------
                                        Name:  Joseph F. Pesce
                                             -----------------------------------
                                        Title: Sole Trustee

                                        This Reaffirmation of Guaranty and
                                        Pledge and Security Agreement is
                                        executed on behalf of ARI National
                                        Company by its sole trustee as sole
                                        trustee and not individually, and the
                                        obligations of ARI National Company
                                        hereunder are not binding upon any of
                                        ARI National Company's sole trustee,
                                        officers or shareholders or any of them
                                        individually but are binding only upon
                                        the assets and property of ARI National
                                        Company. The Agreement and Declaration
                                        of Trust of ARI National Company is on
                                        file with the Secretary of the
                                        Commonwealth of Massachusetts.
<PAGE>

                                  EXHIBIT "A"
                                  -----------

                                 Schedule 1.1

                                  Commitments
                                  -----------

<TABLE>
<CAPTION>
-------------------------------------------------------------------------------------------------------
                        Lender                                           Revolving Commitment
                        ------                                           --------------------
-------------------------------------------------------------------------------------------------------
<S>                                                                      <C>
                 Bank of America, N.A.                                      $9,533,333.34
-------------------------------------------------------------------------------------------------------
GMAC Commercial Credit LLC (formerly BNY Factoring LLC)                     $9,533,333.34
-------------------------------------------------------------------------------------------------------
              FINOVA Capital Corporation                                    $7,800,000.00
-------------------------------------------------------------------------------------------------------
                  PNC Business Credit                                       $7,800,000.00
-------------------------------------------------------------------------------------------------------
         The CIT Group / Business Credit, Inc.                              $7,800,000.00
-------------------------------------------------------------------------------------------------------
                National Bank of Canada                                     $6,066,666.66
-------------------------------------------------------------------------------------------------------
            Citizens Bank of Massachusetts                                  $6,066,666.66
-------------------------------------------------------------------------------------------------------
            Debis Financial Services, Inc.                                  $6,066,666.66
-------------------------------------------------------------------------------------------------------
                     Webster Bank                                           $4,333,333.34
-------------------------------------------------------------------------------------------------------
</TABLE>
<PAGE>

                                  EXHIBIT "B"
                                  -----------

                           Current Letters of Credit
                           -------------------------


<TABLE>
<CAPTION>
----------------------------------------------------------------------------------------------------------------
L/C Number       Expiry Date      Amount                  Beneficiary                      Issuing Bank
----------       -----------      ------                  -----------                      ------------
----------------------------------------------------------------------------------------------------------------
<S>              <C>            <C>              <C>                                     <C>
   1225            7/31/01      $100,000.00      EOP-225 Franklin Street, LLC            Bank of America
----------------------------------------------------------------------------------------------------------------
   1227            7/08/01      $165,797.77      The Equitable Life Assurance            Bank of America
----------------------------------------------------------------------------------------------------------------
 3705028           6/12/01      $325,856.55     600 Lexington Avenue Associates          Bank of America
----------------------------------------------------------------------------------------------------------------
</TABLE>