The UN Sustainable Development Goals of 2015 have restored universal health coverage (UHC) to prominence in the international health agenda. Can understanding the past illuminate the prospects for UHC in the present? This article traces an earlier history of UHC as an objective of international health politics. Its focus is the efforts of the International Labor Organization (ILO), whose Philadelphia Declaration (1944) announced the goal of universal social security, including medical coverage and care. After World War II, the ILO attempted to enshrine this in an international convention, which nation states would ratify. However, by 1952 these efforts had failed, and the final convention was so diluted that universalism was unobtainable. Our analysis first explains the consolidation of ideas about social security and health care, tracing transnational policy linkages among experts whose world view transcended narrow loyalties. We then show how UHC goals became marginalized, through the opposition of employers and organized medicine, and of certain nation states, both rich and poor. We conclude with reflections on how these findings might help us in thinking about the challenges of advancing UHC today.