On December 8, 1953, in the midst of increasing nuclear weapons testing and geopolitical polarization, United States President Dwight D. Eisenhower launched the Atoms for Peace initiative. More than a pacifist program, the initiative is nowadays seen as an essential piece in the U.S. defense strategy and foreign policy at the beginning of the Cold War. As such, it pursued several ambitious goals, and Latin America was an ideal target for most of them: to create political allies, to ease fears of the deadly atomic energy while fostering receptive attitudes towards nuclear technologies, to control and avoid development of nuclear weapons outside the United States and its allies, and to open or redirect markets for the new nuclear industry. The U.S. Department of State, through the Foreign Operations Administration, acted in concert with several domestic and foreign middle-range actors, including people at national nuclear commissions, universities, and industrial funds, to implement programs of regional technical assistance, education and training, and technological transfer. Latin American countries were classified according to their stage of nuclear development, with Brazil at the top and Argentina and Mexico belonging to the group of “countries worthy of attention.” Nuclear programs often intersected with development projects in other areas, such as agriculture and public health. Moreover, Eisenhower’s initiative required the recruitment of local actors, natural resources and infrastructures, governmental funding, and standardized (but localized techno-scientific) practices from Latin American countries. As Atoms for Peace took shape, it began to rely on newly created multilateral and regional agencies, such as the International Atomic Energy Agency (IAEA) of the United Nations and the Inter-American Nuclear Energy Commission (IANEC) of the Organization of American States (OAS). Nevertheless, as seen from Latin America, the implementation of atomic energy for peaceful purposes was reinterpreted in different ways in each country. This fact produced different outcomes, depending on the political, economic, and techno-scientific expectations and interventions of the actors involved. It provided, therefore, an opportunity to create local scientific elites and infrastructure. Finally, the peaceful uses of atomic energy allowed the countries in the region to develop national and international political discourses framing the Treaty for the Prohibition of Nuclear Weapons in Latin America and the Caribbean signed in Tlatelolco, Mexico City, in 1967, which made Latin America the first atomic weapons–free populated zone in the world.