Barrett Business Services (BBSI) 10-Q 2006 Q1 Quarterly report

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 March 31, 2006, 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.

/s/ William W. Sherertz
William W. Sherertz
Chielf Executive Officer
May 12, 2006 /s/ Michael D. Mulholland
Michael D. Mulholland
Chief Financial Officer
May 12, 2006