This book investigates how citizens in the United States and Russia have used the democratic process to force their governments to address the horrendous environmental damage caused by the nuclear arms race. It is the first in-depth comparative study of environmental activism and democracy in the two countries. Critical Masses focuses on two crucial areas - the Hanford Reservation in Washington State and the Mayak Complex in Russia - that were at the heart of their nations' nuclear weapons programs, examining how the surrounding communities were affected. It explores nuclear weapons production, how both governments concealed environmental and health dangers from people living nearby, and how Russian and American citizens think about environmental issues. And it provides insights into the process of democratization in Russia and the limits of democracy in the United States, as well as the development of nuclear policy in the post-Cold War era.