Exhibit 32

CERTIFICATION PURSUANT TO

18 U.S.C. SECTION 1350

In connection with the Quarterly Report of Barrett Business Services, Inc. (the “Company”) on Form 10-Q for the period ended June 30, 2009 as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned certify, pursuant to 18 U.S.C. § 1350, that:

(1) The Report fully complies with the requirements of section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

(2) The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.