This paper discusses the X-31A Enhanced Fighter Maneuverability (EFM) aircraft and program. This program is unique in that its eventual purpose is the demonstration of the tactical utility of Enhanced Fighter Maneuverability after initial generation of in-flight technical data.The genesis of the program is outlined and the design criteria for the aircraft are presented. The impacts of the low cost requirement are described, and the current status of the flight test program is presented.The program is a unique form of collaboration between the U.S. and German governments, Rockwell International Corporation and Messerschmitt-Bolkow-Blohm (MBB). This successful arrangement could form the basis for future international collaborations.This paper is an update of that of Reference 1. Further information on technical details of the aircraft can be found in References 2 and 3.