EXHIBIT 11 BARRETT BUSINESS SERVICES, INC. STATEMENT OF CALCULATION OF AVERAGE COMMON SHARES OUTSTANDING Three Months Ended September 30, 1996 ------------------ Primary Earnings Per Share: Weighted average number of shares 6,776,985 Stock option plan shares to be issued at prices ranging from $3.50 to $18.6875 per share 494,050 Warrant issues at a price of $4.20 per share 90,000 Less: Assumed purchase at average market price during the period using proceeds received upon exercise of options and purchase of stock, and using tax benefits of compensation due to premature dispositions (342,369) --------- Total Primary Shares 7,018,666 ========= Fully Diluted Earnings Per Share: Weighted average number of shares 6,776,985 Stock option plan shares to be issued at prices ranging from $3.50 to $18.6875 per share 494,050 Warrant issues at a price of $4.20 per share 90,000 Less: Assumed purchase at the higher of ending or average market price during the period using proceeds received upon exercise of options and purchase of stock, and using tax benefits of compensation due to premature dispositions (342,369) -------- Total Diluted Shares 7,018,666 =========