The Viability Assessment of a Repository at Yucca Mountain describes the nuclear waste problem and explains why the United States and other nations are considering deep geologic disposal as the solution. The overview describes why the Unites States is considering Yucca Mountain and how a monitored geologic repository would work in the mountain. It presents a repository design, an assessment of its expected performance, and an evaluation of the possible effects on people living near Yucca Mountain. Also presented is the work remaining to be completed prior to a license application, along with the estimated cost of building and operating a geologic repository at Yucca Mountain. Finally, based on the information in the viability assessment, the overview concludes with DOE's assessment of whether work at Yucca Mountain should proceed.