The U.S. Department of Energy (DOE) and its predecessor agencies have conducted activities to develop atomic energy for civilian and defense purposes since the initiation of the World War II Manhattan Project in 1942. These activities took place at large federal land reservations of hundreds of square miles involving industrial-scale operations, but also at many smaller federal and non-federal sites such as uranium mines, materials processing and manufacturing facilities. The nuclear weapons and energy production activities at these facilities produced large quantities of radioactive and hazardous wastes and resulted in widespread groundwater and soil contamination at these sites. DOE initiated a concerted effort to clean up these sites beginning in the 1980s. Many of these sites have been remediated and are in long-term caretaker status, closed or repurposed for other uses. Review of the Effectiveness and Efficiency of Defense Environmental Cleanup Activities of the Department of Energy's Office of Environmental Management: First Report provides background information on the sites currently assigned to the DOE's Office of Environmental Management that are undergoing cleanup; discusses current practices for management and oversight of the cleanups; offers findings and recommendations on such practices and how progress is measured against them; and considers the contracts under which the cleanups proceed and how these have been and can be structured to include incentives for improved cost and schedule performance.