Simpson Manufacturing Company is a leading building materials manufacturer in the United States that produces structural connectors, fasteners, anchors, and products for new construction and retrofitting.

The company was founded by Barclay Simpson in Oakland in 1956, as a successor to his father's window screen company. Simpson manufactured joist hangers and the company's subsidiary Simpson Strong-Tie Co. Inc. became a dominant producer of structural connectors in North America and Europe. The company subsequently moved to Pleasanton and went public in 1994.