The Department of Defense (DOD) established the military munitions response program (MMRP) in 2001 to clean up sites known to be or suspected of being contaminated with military munitions and related hazardous substances. Cleanup of sites on active and base realignment and closure installations is the responsibility of the military service, Air Force, Army, Navy, or Marine Corps, that currently controls the land, and the Army has delegated execution of cleanup of formerly used defense sites (FUDS) to the U.S. Army Corps of Engineers (Corps). GAO was mandated to assess the (1) MMRP staffing and funding levels; (2) progress DOD has made in cleaning up munitions response sites; (3) extent to which DOD has established MMRP performance goals; and (4) extent to which DOD collects data on factors influencing project duration, as well as the accuracy of its cleanup cost estimates. GAO analyzed MMRP data and DOD documents and interviewed officials from DOD, the military services, and the Corps. GAO recommends that Congress consider requiring DOD to report separately on sites where response is complete because they needed no cleanup, and that DOD issue guidance on how factors other than relative risk should be considered in munitions response site sequencing decisions, and set FUDS performance goals as required by law. DOD partially agreed with the recommendations but not with the matter for congressional consideration.