The Department of Energy is responsible for treating and disposing of waste from nuclear weapons production and energy research. Its projects for building treatment facilities and demolishing old buildings have often been over budget and delayed. DOE project management has been on our High Risk List since 1990. We reviewed DOE oversight of 5 contracted projects. In the only project ahead of schedule and under budget, contractors maintained consistent, reliable project data in systems that oversight officials could use to find problems promptly. We recommended ensuring contractors maintain good project data systems, and more.