ABSTRACT Early efforts to bring particle accelerators into Brazil exemplify the interactions between advanced scientific countries and the periphery in the years 1948––1956 and between the history of science and the history of foreign affairs. The physicists Cesar Lattes, Ernest Lawrence, Herbert Anderson, Isidor Rabi, and Rear Admiral ÁÁlvaro Alberto played central roles in these efforts. The story brings out the role of the military and scientists acting within the Centro Brasileiro de Pesquisas Fíísicas and the Conselho Nacional de Pesquisas to promote nuclear physics research aimed at the development of nuclear technology in Brazil. The decision-making process involved science, politics, secret agreements, and international affairs.