While the Cold War between the United States and Soviet Union was a "long peace" noted for its political stability, the Cold War in the global South – defined as Latin America, Asia, and Africa – was hardly peaceful. Instead, it was dominated by volatility, political extremism, and bloodshed. In Argentina during the Cold War, for example, the country was torn between the violence of revolutionary guerrilla groups and a series of oppressive, anti-Communist dictatorships backed by the United States. This interdisciplinary project, situated between Cold War political history and social studies of science, technology, and medicine, examines how the Argentine psychological sciences interacted with the violence, volatility, and extremism endemic to the global South during the Cold War. Most Cold War studies focus on social science under the peace and massive military resources of the U.S. and Soviet Union. My dissertation research turns to Argentina to explore how social science was constituted – not in the rather isolated cases of stability and wealth in the northern superpowers – but amid the violence and extremism that defined politics for the vast majority of nations during the global Cold War. At the height of political violence in Argentina from 1966 to 1983, military officials and activist organizations mobilized scientific understandings of the mind to advance Cold War ideologies and attack political enemies. While the military labeled guerrilla fighters "psychopaths," activist organizations partnered with psychologists to defend political resistance and criticize the psychological effects of state terror. Relying on historical archives and interviews in Argentina, I argue that Argentine psychology offers an invaluable window into the volatile politics that defined the Cold War in the South and reveals an ideologically-committed brand of scientific practice that complicates dominant narratives of Cold War social science based on the First World.