Geoffrey G. Diehl is a Republican politician who represents the 7th Plymouth District (Abington, Whitman, and East Bridgewater) in the Massachusetts House of Representatives. He is a member of the House Committee on Ways and Means, House Committee on Rules, and House Committee on Personnel and Administration. Representative Diehl is also a member of the House Library Caucus and Regional School Caucus. On November 2, 2010 he upset incumbent Allen McCarthy and was sworn in on January 5, 2011.