<PAGE>

                                                                   Exhibit 10.23

                      SEVENTH AMENDMENT TO CREDIT AGREEMENT

     This SEVENTH AMENDMENT TO CREDIT AGREEMENT (this "Amendment") is dated as
of March 19, 2002, and is entered into by and among Opinion Research
Corporation, a Delaware corporation ("Parent"), ORC INC., a Delaware corporation
("ORC", Parent and ORC are sometimes collectively referred to herein as the
"Borrowers" and individually as a "Borrower"), the Subsidiaries of Borrowers
party hereto, Heller Financial, Inc., in its capacity as Agent for the Lenders
party to the Credit Agreement described below ("Agent"), and the Lenders which
are signatories hereto.

     WHEREAS, Agent, Lenders and Borrowers are parties to a certain Credit
Agreement dated as of May 26, 1999 (as such agreement has from time to time been
amended, supplemented or otherwise modified, the "Agreement"); and

     WHEREAS, the parties desire to amend the Agreement as hereinafter set
forth.

     NOW, THEREFORE, in consideration of the mutual conditions and agreements
set forth in the Agreement and in this Amendment, and other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
parties hereto hereby agree as follows:

     1.   Definitions. Capitalized terms used in this Amendment, unless
otherwise defined herein, shall have the meaning ascribed to such terms in the
Agreement.

     2.   Amendments to Agreement. Subject to the conditions set forth below,
the Agreement is amended as follows:

          (a)   Section 4.1 of the Agreement shall be amended in its entirety
and as so amended shall read as follows:

          "4.1  Capital Expenditure Limits. The aggregate amount of all Capital
     Expenditures of Parent and its Subsidiaries will not exceed $5,000,000 in
     any fiscal year (other than the fiscal year ending December 31, 2002, in
     which case the aggregate amount of all Capital Expenditures of Parent and
     its Subsidiaries made in such fiscal year will not exceed $4,500,000), but
     in no event in excess of such lesser amount as may be permitted under the
     Subordinated Loan Agreement (the "Capex Limit"). Notwithstanding the
     foregoing, and to the extent permitted under the Subordinated Loan
     Agreement, in the event Parent and its Subsidiaries do not expend the
     entire Capex Limit permitted in any fiscal year, Parent and its
     Subsidiaries may carry forward to the immediately succeeding fiscal year
     50% of the unutilized portion of the Capex Limit (provided, however, that
     no such carry forward shall be permitted with respect to any unutilized
     portion of the Capex Limit for the fiscal year ending December 31, 2001).
     All Capital Expenditures

                                        1

<PAGE>

     made by Parent and its Subsidiaries shall first be applied to reduce the
     applicable Capex Limit and then to reduce the carry forward from the
     previous fiscal year, if any. "Capital Expenditures" will be calculated as
     illustrated on Exhibit 4.8(C)."

          (b)   Section 4.3 of the Agreement shall be amended by (i) deleting
the dollar amount "$17,000,000" set forth opposite the date March 31, 2002 and
inserting in lieu thereof the dollar amount "14,500,000"; (ii) deleting the
dollar amount "$17,000,000" set forth opposite the date June 30, 2002 and
inserting in lieu thereof the dollar amount "$15,000,000"; (iii) deleting the
dollar amount "$17,000,000" set forth opposite the date September 30, 2002 and
inserting in lieu thereof the dollar amount "$15,750,000"; and (iv) deleting the
dollar amount "$17,500,000" set forth opposite the date December 31, 2002 and
inserting in lieu thereof the dollar amount "$16,500,000".

          (c)   Subsection (B) of Section 4.4 of the Agreement shall be amended
in its entirety and as so amended shall read as follows:

          "(B)  Borrowers shall not permit Fixed Charge Coverage for any twelve
     (12) month period ending on the last day of any calendar quarter to be less
     than: (i) 1.05 for each of the calendar quarters ending March 31, 2002,
     June 30, 2002, September 30, 2002 and December 31, 2002 and (ii) 1.20 for
     any other calendar quarter."

          (d)   Subsection (B) of Section 4.5 of the Agreement shall be amended
in its entirety and as so amended shall read as follows:

          "(B)  Borrowers shall not permit Total Interest Coverage for any
     twelve (12) month period ending on the last day of any calendar quarter
     ending on any date set forth below to be less than the ratio set forth
     below for such period:

          Period Ending                                        Ratio
          -------------------------------------------          -----
          December 31, 2000 through December 31, 2001           2.50
          March 31, 2002                                        2.25
          June 30, 2002                                         2.25
          September 30, 2002                                    2.25
          December 31, 2002                                     2.50
          March 31, 2003 & the last day of each
           calendar quarter thereafter                          2.75"

          (e)   Section 4.6 of the Agreement shall be amended in its entirety
and as so amended shall read as follows:

          "4.6  Senior Indebtedness to Adjusted EBITDA Ratio. Borrowers shall
     not permit the ratio of Senior Indebtedness calculated as of the last day
     of any calendar quarter ending during any of the periods set forth below to
     Adjusted

                                        2

<PAGE>

     EBITDA for the twelve (12) month period ending on such day to be greater
     than the amount set forth below for such period:

          Period Ending                                        Amount
          -------------------------------------------          ------
          June 30, 1999 through September 30, 2000               3.00
          December 31, 2000 through December 31, 2001            2.75
          March 31, 2002                                         2.80
          June 30, 2002                                          2.75
          September 30, 2002                                     2.50
          December 31, 2002 & the last day of each
           calendar quarter thereafter                           2.25
          "Senior Indebtedness" shall be calculated as illustrated on
          Exhibit 4.8(C)."

          (f)   Section 4.7 of the Agreement shall be amended in its entirety
and as so amended shall read as follows:

          "4.7  Indebtedness to Adjusted EBITDA Ratio. Borrowers shall not
     permit the ratio of Total Indebtedness calculated as of the last day of any
     calendar quarter ending during any of the periods set forth below to
     Adjusted EBITDA for the twelve (12) month period ending on such day to be
     greater than the amount set forth below for such period:

          Period Ending                                        Amount
          --------------------------------------------         ------
          June 30, 1999 through September 30, 2000               4.00
          December 31, 2000 through September 30, 2001           3.75
          December 31, 2001                                      3.50
          March 31, 2002                                         3.80
          June 30, 2002                                          3.75
          September 30, 2002                                     3.50
          December 31, 2002 & the last day of each
           calendar quarter thereafter                           3.25

          "Total Indebtedness" shall be calculated as illustrated on
          Exhibit 4.8(C)."

     3.   Conditions. The effectiveness of this Amendment is subject to the
following conditions precedent:

          (a)   Borrowers shall have executed and delivered this Amendment, and
such other documents and instruments as Agent may require shall have been
executed and/or delivered to Agent (including, without limitation, true,
complete and correct copies of fully executed documents amending the
Subordinated Loan Agreement in form and substance acceptable to Agent and
Required Lenders);

                                        3

<PAGE>

          (b)   All proceedings taken in connection with the transactions
contemplated by this Amendment and all documents, instruments and other legal
matters incident thereto shall be satisfactory to Agent and its legal counsel;

          (c)   No Default or Event of Default shall have occurred and be
continuing;

          (d)   The representations and warranties set forth in Section 4 below
are true, correct and complete; and

          (e)   Borrowers shall have paid to Agent a non-refundable amendment
fee in the amount of one-quarter of one percent (0.25%) of the "Aggregate
Commitment", such amendment fee to be shared by the Lenders who have executed
this Amendment pro rata based on each Lender's respective share of the Aggregate
Commitment (for purposes of this clause (e), "Aggregate Commitment" shall mean,
with respect to the Lenders who have executed this Amendment, the aggregate
Revolving Loan Commitment of such Lenders plus the outstanding principal amount
of Term Loans of such lenders, in each case calculated as of the date hereof).

     4.   Representations and Warranties. To induce Agent and Lenders to enter
into this Amendment, each of the Borrowers represents and warrants to Agent and
Lenders:

          (a)   that the execution, delivery and performance of this Amendment
has been duly authorized by all requisite corporate action on the part of such
Borrower and that this Amendment has been duly executed and delivered by such
Borrower; and

          (b)   that each of the representations and warranties set forth in
Section 5 of the Agreement (other than those which, by their terms, specifically
are made as of certain date prior to the date hereof) are true and correct in
all material respects as of the date hereof.

     5.   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.

     6.   References. Any reference to the Agreement contained in any document,
instrument or agreement executed in connection with the Agreement shall be
deemed to be a reference to the Agreement as modified by this Amendment.

     7.   Counterparts. This Amendment may be executed in one or more
counterparts, each of which shall constitute an original, but all of which taken
together shall be one and the same instrument.

     8.   Ratification. The terms and provisions set forth in this Amendment
shall modify and supersede all inconsistent terms and provisions of the
Agreement and shall not be deemed to be a consent to the modification or waiver
of any other term or condition of the Agreement.

                                        4

<PAGE>

Except as expressly modified and superseded by this Amendment, the terms and
provisions of the Agreement are ratified and confirmed and shall continue in
full force and effect.

     9.   Reaffirmation. Each Loan Party party hereto has executed and delivered
one or more of the Security Documents and/or the other Loan Documents as debtor,
grantor, pledgor, guarantor, assignor, or in other similar capacities in which
such Person has granted liens or security interests in their respective
properties or otherwise acted as an accommodation party or guarantor, as the
case may be. Each Loan Party party hereto hereby ratifies and reaffirms all of
its respective payment and performance obligations, contingent or otherwise,
under the Security Documents and any other Loan Documents to which it is a party
and, to the extent any such Person has granted liens on or security interests in
any of their respective properties pursuant to any of the Security Documents or
any of the other Loan Documents as security for or otherwise guaranteed the
Obligations under or with respect to the Agreement or any other Loan Documents,
hereby ratifies and reaffirms such payment and performance obligations,
guarantee and grant of security interests and liens and confirms and agrees that
such security interests and liens hereafter secure all of the Obligations. Each
Loan Party party hereto agrees that each of the Security Documents and each
other Loan Document remains in full force and effect and is hereby ratified and
reaffirmed, and agrees that the Amendment shall not (i) operate as a waiver of
any right, power or remedy of Agent or Lenders under the Loan Documents or (ii)
constitute a waiver of any provision of any of the Loan Documents or serve to
effect a novation of the Obligations.

         [rest of page intentionally left blank; signature page follows]

                                        5

<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be
duly executed under seal and delivered by their respective duly authorized
officers on the date first written above.

AGENT and LENDERS:                          BORROWERS:

Heller Financial, Inc.,                     OPINION RESEARCH CORPORATION,
as Agent and as a  Lender                   a Delaware corporation

By:      /s/ Francois Delangle              By:     /s/ Douglas L. Cox
   ------------------------------------     ------------------------------------
Name:        Francois Delangle              Name:       Douglas L. Cox
     ----------------------------------     ------------------------------------
Title:       Vice President                 Title:      Executive Vice President
      ---------------------------------     ------------------------------------

FIRST UNION NATIONAL BANK,                  ORC INC.,
as a Lender                                 a Delaware corporation

By:      /s/ Daniel Evans                   By:     /s/ Kevin P. Croke
   ---------------------------------        ------------------------------------
Name:        Daniel Evans                   Name:       Kevin P. Croke
     -------------------------------        ------------------------------------
Title:       Managing Director              Title:      President
      ------------------------------        ------------------------------------

FLEET NATIONAL BANK,
as a Lender

By:      /s/ Thomas Hamilton
   ------------------------------------
Name:         Thomas Hamilton
     ----------------------------------
Title:        Assistant Vice President
      ---------------------------------

MERRILL LYNCH BUSINESS FINANCIAL SERVICES, INC.,
as a Lender

By:      /s/ Daniel J. McHugh
   -----------------------------------
Name:         Daniel J. McHugh
     ---------------------------------
Title:        Vice President
      --------------------------------

PNC BANK, NATIONAL ASSOCIATION,
as a Lender

By:      /s/ Jeffrey A. Blakemore
   ---------------------------------
Name:         Jeffrey A. Blakemore
     -------------------------------
Title:       Senior Vice President
      ------------------------------


                       [signatures continued on next page]


Seventh Amendment to Credit Agreement

<PAGE>

SUBSIDIARIES:

ORC TELESERVICE CORP.,
a Delaware corporation

By:      /s/ Kevin P. Croke
   -----------------------------------------
Name:        Kevin P. Croke
     ---------------------------------------
Title:       Secretary
      --------------------------------------


ORC PROTEL, INC.,
a Delaware corporation

By:      /s/ Kevin P. Croke
   -----------------------------------------
Name:        Kevin P. Croke
     ---------------------------------------
Title:      Secretary
      --------------------------------------


MACRO INTERNATIONAL, INC.,
a Delaware corporation

By:      /s/ Douglas L. Cox
   -----------------------------------------
Name:         Douglas L. Cox
     ---------------------------------------
Title:       Secretary
      --------------------------------------


SOCIAL AND HEALTH SERVICES, LTD.,
a Maryland corporation

By:      /s/ Kevin P. Croke
   -----------------------------------------
Name:         Kevin P. Croke
     ---------------------------------------
Title:        Secretary
      --------------------------------------


ORC CONSUMER, INC.,
a Delaware corporation

By:
   -----------------------------------------
Name:
     ---------------------------------------
Title:
      --------------------------------------

Seventh Amendment to Credit Agreement