EXHIBIT 23.3

RP^® financial, lc.

Financial Services Industry Consultants

August 29, 2006

Board of Directors
FirstBank NW Corp.
1300 16th Avenue
Clarkston, Washington 99403

RE: Consent of RP^® Financial, LC. (“RP Financial”)

Members of the Board:

     We hereby consent to the inclusion of our opinion letter, dated June 4, 2006, to the Board of Directors of FirstBank NW Corp. as an Exhibit to the Proxy Statement/Prospectus relating to the proposed merger by and between FirstBank NW Corp. and Sterling Financial Corporation contained in Sterling Financial Corporation’s Registration Statement on Form S-4 as filed with the Securities and Exchange Commission, and to the references to our firm and such opinion in such Proxy Statement/Prospectus. In giving such consent, we do not admit that we come within the category of persons whose consent is required under Section 7 of the Securities Act of 1933, as amended (the “Act”), or the rules and regulations of the Securities and Exchange Commission thereunder (the “Regulations”), nor do we admit that we are experts with respect to any part of such Registration Statement within the meaning of the term “experts” as used in the Act or Regulations.

Sincerely,

RP^® FINANCIAL, LC.

Washington Headquarters
Rosslyn Center	Telephone: (703) 528-1700
1700 North Moore Street, Suite 2210	Fax No.: (703) 528-1788
Arlington, VA 22209	Toll-Free No.: (866) 723-0594
www.rpfinancial.com	E-Mail: mail@rpfinancial.com