This exhibition was organized to commemorate the fiftieth anniversary of the world's first controlled, self-sustaining nuclear chain reaction, an achievement of Enrico Fermi and his colleagues at the Metallurgical Laboratory at the University of Chicago. Based on the papers of individual scientists and records of scientists' associations, the text of this exhibition provides an account of the construction and operation of the first nuclear pile beneath the West Stands of Stagg Field on the campus of the University of Chicago. The exhibition explores the concerns of atomic scientists from Chicago and elsewhere about the dangers of nuclear power, and it displays documents and photographs depicting the scientists' post-World War II campaigns of public education and legislation to assure civilian control of atomic energy.