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 March 31, 2004, as filed with the Securities and Exchange Commission on the date hereof (the "Report"), the undersigned certify, pursuant to 18 U.S.C. ss. 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 /s/ Michael D. Mulholland - ----------------------- --------------------------------- William W. Sherertz Michael D. Mulholland Chief Executive Officer Chief Financial Officer May 14, 2004 May 14, 2004