The development of nuclear science in Iran predates the 1979 Islamic Revolution and emerged as part of a broader modernization strategy pursued during the reign of Shah Mohammad Reza Pahlavi. Beginning in the 1950s through cooperation with the United States under the "Atoms for Peace" program, Iran established research institutions, trained nuclear scientists, acquired research reactors, and launched ambitious plans for nuclear power generation. By the late 1970s, Iran possessed a growing scientific community, an institutional framework for nuclear research, and several major international nuclear agreements. This article examines the origins, institutional development, scientific infrastructure, and international partnerships that shaped Iranian nuclear science before 1979.