This is a review of the FAA¿s oversight of air carriers¿ outsourced aircraft maintenance. As of July 14, 2008, there were 4,159 domestic and 709 foreign repair stations certificated by FAA to perform maintenance on U.S. aircraft. When an air carrier uses an FAA-certificated repair station to repair its aircraft or parts, the repair station¿s organization becomes an extension of the air carrier¿s maintenance organization. This report: (1) identifies the type and quantity of maintenance performed by external repair stations; and (2) determines whether FAA is effectively monitoring air carriers¿ oversight of external repair stations¿ work and verifying that safety requirements are met. Illustrations.