This solid book carefully outlines the essentially political role of American scientists in this country's nuclear weapons policy since 1945. At the end of World War II, American scientists generally desired international control of atomic energy as envisaged in the Baruch Plan. With the advent of the Cold War, however, scientists split into two camps: a smaller group which thought we should pursue international control at all costs, and a larger group that reluctantly concluded we must develop nuclear armaments in the face of Russian expansion. After the Russians had proved their atomic capacity in 1949, this latter group was to divide on the question of developing the hydrogen bomb. Mr. Gilpin gives a clear view of the alternative policy (involving, especially, diversified conventional forces to meet limited aggression) which those who opposed a crash program for an H-bomb, including Oppenheimer, proposed. Finally, much of the book is devoted to conflicting scientific opinions of the nuclear test moratorium and the diplomatic duping of American scientists at the Geneva conference of 1958. Eschewing the cloak-and-dagger plots of C.P. Snow, Mr. Gilpin writes with scrupulous dispassion.