Kelly Services Inc. (NASD: KELYA) acquired Teachers On Call, the sixth-largest education staffing firm in the US, expanding its position in the K-12 market.

The transaction closed Sept. 5 and terms were not disclosed. Teachers On Call will operate under its own brand with its current staff, but President and CEO Kim Howard is retiring from the company.

Founded in 1999 and headquartered in Bloomington, Minn., Teachers On Call provides substitute education professionals to more than 110 school districts throughout Minnesota and Wisconsin, as well as to more than 150 charter schools and early child care centers in the Twin Cities metro area. The company is currently expanding into Iowa.

Kelly Educational Staffing is the largest education staffing firm in the US, according to Staffing Industry Analysts’ research.

“We’re delivering a complete education talent management solution,” said Nicola Soares, VP and managing director of Kelly Educational Staffing, who now also leads Teachers On Call. “Not only are both companies addressing the full-time teacher shortage head-on, this acquisition also expands our market leadership to a wider geographic area and an even broader set of talent needs, including early child care centers.”

The deal marks the second recent transaction in the education staffing sector. In July, Source4Teachers — which was previously ranked by SIA as the second-largest education staffing firm — joined Education Solutions Services LLC.

Kelly Educational Staffing, launched in 1997, serves more than 7,000 schools across 35 states. It provides substitute teacher staffing and management; after school program staffing; and the staffing of non-instructional positions such as custodians, cafeteria employees, administrative assistants and school nurses.

“This acquisition demonstrates that even though Kelly is already leading the education market, we have no intention of slowing down,” said Kelly Services President and CEO George Corona.