Conventional understandings of the post-WWII multilateral order locate its origins in the negotiations between an ascendant United States and a Europe wracked by war, with a peripheral role, at best, played by countries of the colonized and less-developed world. This project, however, will ask how the interwar internationalism of the less-developed world influenced how the world powers sought to organize global governance after the Second World War. Against the notion that liberal multilateralism was antithetical to economic and political nationalism, my preliminary research has uncovered successive efforts by post-Revolutionary Mexican nationalists, from the Paris Peace Conference in 1919 through the Bretton Woods economic conference in 1944, to structure a multilateral system of economic and political cooperation—and to thereby codify a “revolutionary internationalism” that would address the global distribution of power and resources. Projecting outward the nationalism engendered by the recent Mexican Revolution, interwar Mexican intellectuals, jurists, and diplomats repeatedly sought to codify a vision of state-vested property rights, absolute sovereignty, and national developmentalism in international legal frameworks, agreements, and institutions. By utilizing a variety of archival sources in Mexico and the United States, including diplomatic, scholarly, and personal records, this project will present a transnational analysis of Mexico’s continued advocacy of multilateral cooperation in the interwar period, and will propose that that advocacy directly challenged the U.S. conception of multilateral liberalism—not through its rejection, but rather through its extension into economic and social realms. That challenge, I hypothesize, was instrumental in embedding the idea of “development” into international institutions, and directly shaped how the United States envisioned the postwar multilateral order and projected its power in the world.