Administaff Inc. (NYSE: ASF) reported a 10.1% increase in third-quarter revenue to $421.9 million from $383.4 million in the same period last year. The Houston-based professional employer organization posted a 6.1% increase in the average number of worksite employees paid per month and a 3.7% increase in revenue per worksite employee per month.

Gross margin improved to 20.3% from 19.6%.

Third-quarter net income, however, fell 1.9% to $11.9 million from $12.2 million in the third quarter of 2008.

Administaff ranks as the largest PEO by net revenue, according to Staffing Industry Analysts' list of largest PEOs.

Administaff Inc. (NYSE: ASF)
For the third quarter ended Sept. 30, 2008, compared with the same period in 2007.
Revenue: $421.9 million, +10.1%
Net income: $11.9 million, -1.9%