This article shows how John Maynard Keynes's lifelong commitment to eugenics was deeply embedded in his political, economic, and philosophical work. At the turn of the century, eugenics seemed poised to grant industrial nations unprecedented control over their own future, but that potential depended on contested understandings of the biological mechanisms of inheritance. Early in his career, Keynes helped William Bateson, Britain's chief proponent of Mendelian genetics, analyze problems in human heredity. Simultaneously, Keynes publicly opposed the efforts by Francis Galton and Karl Pearson to study inheritance through statistical biometry. For Keynes, this conflict was morally laden: Mendelism incorporated the only ethical theory of uncertainty, while biometry rested on false and dangerous concepts. This early study of heredity shaped Keynes's visions of industrial democracy after 1918. Liberals looked for a system of societal and economic management to engineer an escape from the postwar Malthusian trap. Britain's economic plight, Keynes argued, was rooted in the hereditary weaknesses of its leadership. Successful technocratic liberalism would depend on control over the quality as well as quantity of human beings. Ultimately, in his essay “Economic Possibilities for Our Grandchildren,” Keynes predicted that effective eugenic management would bring about capitalism's end.