This thesis uses role theory to investigate the motivations of national leaders considering the acquisition of nuclear weapons. The correlation between expressed roles and proliferation decisionmaking is examined in the cases of Brazil and India within the framework of a most similar systems design. The material and ideational sources of Brazilian and Indian national role conceptions are traced using a model developed by Marijke Breuning (2011). In the Brazilian case, the expressed national role conceptions are found to be inconsistent with acquisition of nuclear weaponry, whereas in the Indian case, nuclear explosives were seen as powerful symbols consistent with the role conceptions of national iv leaders. The insights yielded by role theory in these cases provide a valuable addition to the existing nonproliferation literature.