Exhibit 5.1

THACHER
 PROFFITT
- ---------
THACHER PROFFITT & WOOD LLP

                                                    Thacher Proffitt & Wood LLP
                                                    1700 Pennsylvania Avenue, NW
                                                    Suite 800
                                                    Washington, DC 20006
                                                    (202) 347-8400

                                                    Fax: (202) 626-1930
                                                    www.tpw.com

                                           September 4, 2007

Board of Directors
Westfield Financial, Inc.
141 Elm Street
Westfield, Massachusetts 01085

              Re:    Registration Statement on Form S-8
                     ----------------------------------

Members of the Board:

      We have acted as counsel for Westfield  Financial,  Inc., a Massachusetts
corporation  (the  "Company"),  in connection with the filing of a registration
statement  on  Form  S-8  under  the   Securities   Act  of  1933,  as  amended
("Registration  Statement")  with respect to 2,184,142  shares of the Company's
common  stock,  par value $0.01 per share (the "Common  Stock"),  to be offered
pursuant  to the  Westfield  Financial,  Inc.  2007 Stock  Option  Plan and the
Westfield  Financial,  Inc. 2007 Recognition and Retention  (collectively,  the
"Plans").

      In rendering  the opinion set forth below,  we do not express any opinion
concerning  law  other  than  the  corporate  laws  of the  state  and  federal
securities law.

      We have examined originals or copies,  certified or otherwise identified,
of such documents,  corporate  records and other  instruments as we have deemed
necessary or advisable for purposes of this opinion.  As to matters of fact, we
have  examined  and relied upon the Plans  described  above and,  where we have
deemed appropriate,  representations or certificates of officers of the Company
or  public  officials.  We  have  assumed  the  authenticity  of all  documents
submitted to us as originals,  the  genuineness  of all  signatures,  the legal
capacity  of  natural  persons  and  the  conformity  to the  originals  of all
documents submitted to us as copies.

      Based on the  foregoing,  we are of the opinion that the shares of Common
Stock that are being  registered  pursuant to the  Registration  Statement have
been duly authorized and, when issued and paid for in accordance with the terms
of  the  Plans,   such   shares  will  be  validly   issued,   fully  paid  and
non-assessable.

      In rendering the opinion set forth above,  we have not passed upon and do
not purport to pass upon the  application of "doing  business" or securities or
"blue-sky" laws of any jurisdiction (except federal securities law).


Board of Directors
Westfield Financial, Inc.
September 4, 2007                                                        Page 2

      This  opinion  is  given  solely  for  the  benefit  of the  Company  and
purchasers of shares under the Plans,  and may not be relied upon by any person
or entity,  nor quoted in whole or in part,  or  otherwise  referred  to in any
document without our express written consent.

      We  consent  to  the  filing  of  this  opinion  as  an  exhibit  to  the
Registration Statement and to the references to our firm's name therein.

                                       Very truly yours,

                                       /s/ Thacher Proffitt & Wood LLP

                                       THACHER PROFFITT & WOOD LLP