This biography presents the life of Leo Szilard, an important figure in the creation of the atomic bomb and later an opponent to its use and the use of other nuclear weapons. It includes information on his childhood, education, and role in the making of the atomic bomb, and it also extensively treats his life after the bombs were dropped on Japan. The authors describe his lobbying in 1945 for civilian control of atomic energy, his participation in talks between the U.S. and the Soviet Union, and his founding of the Council for a Livable World, the first political action committee for arms control. They also explain his career change from physics to biology and his establishment of a think tank for science and social issues, the Salk Institute for Biological Studies.