AMENDMENT NO. 1

                                       TO

                    AMENDED AND RESTATED EMPLOYMENT AGREEMENT

                          Dated as of December 31, 2004

         Reference  is made to that  certain  Amended  and  Restated  Employment
Agreement dated as of January 1, 2004 (the  "Agreement") by and among Enterprise
Bancorp,  Inc. (the "Company") and Enterprise Bank and Trust Company (the "Bank"
and  together  with the  Company,  the  "Employers")  and Richard W. Main.  (the
"Executive").

         WHEREAS,  the Employers desire to continue to employ the Executive with
a change in the titles held by the Executive;

         AND WHEREAS, the Executive is willing to continue to be employed with a
change in the titles held by the  Executive  and, in connection  therewith,  has
delivered  on the date  hereof a written  consent  to such  change in titles for
purposes of Section 1.7 of the Agreement;

         NOW,  THEREFORE,  in consideration of the premises and mutual covenants
herein contained and for other good and valuable consideration,  the receipt and
adequacy of which is hereby acknowledged, the Employers and the Executive hereby
agree as follows:

         As of the date set forth above,  the  Agreement  shall be and hereby is
amended,  such that  Sections  1.7, 2 and 4.1 shall be and hereby are amended as
set forth below.

         Amendment to Section 1.7. In Section 1.7,  clause  (a)(i)  contained in
the second and third lines thereof shall be amended and restated in its entirety
to read as follows:

         (a) without the written  consent of the  Executive,  (i) the  Employers
         fail to appoint or reappoint  the Executive as President of the Company
         and President and Chief Lending Officer of the Bank,

         Amendment to Section 2. In Section 2, the first sentence  thereof shall
be amended and restated in its entirety to read as follows:

         Subject to the terms and  provisions set forth in this  Agreement,  the
         Employers, during the Term of Employment, agree to employ the Executive
         as President of the Company and President and Chief Lending  Officer of
         the Bank and the Executive hereby accepts such employment.

         Amendment to Section 4.1. In Section  4.1, the first  sentence  thereof
shall be amended and restated in its entirety to read as follows:

         During the Term of  Employment,  the  Executive  shall be employed  and
         shall serve as President of the Company and President and Chief Lending
         Officer of the Bank.

         The  Agreement,  as  amended  by this  Amendment  No.  1, is and  shall
continue  to be in full  force and  effect  and shall  not be  affected  by this
Amendment No. 1, except and only to the extent specified above.

         IN WITNESS WHEREOF, the undersigned Executive has hereunto set his hand
and each of the Employers has caused this  Amendment No. 1 to be executed in its
name  and on its  behalf  by a duly  authorized  officer,  in  each  case  as an
instrument under seal and as of the date set forth above.

                                ENTERPRISE BANCORP, INC.


                                By: /s/ George L. Duncan
                                   ---------------------------------------------
                                    George L. Duncan
                                    Chairman and Chief Executive Officer



                                ENTERPRISE BANK AND TRUST COMPANY


                                By: /s/ George L. Duncan
                                   ---------------------------------------------
                                    George L. Duncan
                                    Chairman and Chief Executive Officer



                                EXECUTIVE


                                /s/ Richard W. Main
                                ---------------------------------------
                                Richard W. Main