Since the first atomic weapon was detonated in 1945, Canadians have debated not only the role of nuclear power in their uranium-rich land but also their country’s role in a nuclear world. Should Canada belong to international alliances that depend on the threat of nuclear weapons for their own security? Should Canadian-produced nuclear technologies be exported? What about the impact of atomic research on local communities and the environment? This incisive nuclear history engages with much larger debates about national identity, Canadian foreign policy contradictions during the Cold War, and Canada’s global standing to investigate these critical questions.