The National Association of Professional Employer Organizations (NAPEO) said gross revenue for PEOs rose 15% to $61 billion in 2007. Gross revenue is defined as total receipts, which can include billings for payroll and employment-related taxes and insurance.

An estimated 2 million workers are covered by PEOs. And the average NAPEO members' client company employs 19 workers. NAPEO has 400 member PEOs operating in 50 states.