This dissertation examines postwar anti-poverty programs in order to understand the Latin American roots of US social policy, the origins of neoliberalism, and the rise of economists as public intellectuals. By following veterans of the New Deal and Marshall Plan through Colombian reform projects of the 1950s and 1960s and back to the United States in the era of the Great Society, it suggests that one way of studying the route from the 1930s to the 1960s in the United States is by traveling through Latin America. Conversely, one way of understanding the history of economic development is by analyzing its relation to First-World programs for economic recovery and redistribution. The dissertation further illuminates the role of midcentury policymaking in popularizing what became neoliberal practices after 1980, most importantly those of state decentralization, gentrification, and public-private partnership. Finally, midcentury social programs provide a context in which to study the emergence of economics as an independent discipline in Latin America, economists' strategies of social ascent, and the popularization of economic reasoning as a persuasive form of public argument. The project is a social history of economic thought, in which reform projects and the conflicts surrounding them provide the context for studying ideas. It is simultaneously a transnational history of social policy, exposing lines of mutual influence between the United States and Latin America.