Before the passage of federal environmental legislation in the 1970s and 1980s, Department of Defense (DOD) activities contaminated millions of acres of soil and water on and near DOD sites. The Environmental Protection Agency (EPA) has certain oversight authorities for cleaning up contaminants on federal property, and has placed 1,620 of the most contaminated sites, including 141 DOD installations, on its National Priorities List (NPL). As of February 2009, after 10 or more years on the NPL, 11 DOD installations had not signed the required interagency agreements (IAG) to guide cleanup with EPA. GAO was asked to examine (1) the status of DOD cleanup of hazardous substances at selected installations that lacked IAGs, and (2) obstacles, if any, to cleanup at these installations. GAO selected and visited three installations, reviewed relevant statutes and agency documents, and interviewed agency officials. GAO is recommending, among other things, that EPA and DOD identify options that would provide a uniform method for reporting cleanup progress at the installations and allow for transparency to Congress and the public. EPA and DOD agreed with the recommendations directed at them. GAO is also suggesting that Congress may want to consider giving EPA certain tools to enforce CERCLA at federal facilities without IAGs. DOD disagreed with this suggestion. GAO believes EPA needs additional authority to ensure timely and proper cleanup at such sites.