The 331st Fighter-Interceptor Squadron is an inactive United States Air Force unit. Its last assignment was with Air Defense Command at Webb Air Force Base, Texas, where it was inactivated on 1 March 1967. During World War II the squadron was a Lockheed P-38 Lightning replacement training unit on the west coast of the United States. It performed this mission until it was disbanded in 1944 in a major reorganization of Army Air Forces training and support units.