America’s new global power after 1945 was central to the rise of universal human rights as a set of practices and ideals. The new moral language thrived when it received official US backing and usually withered when it did not. Domestic and transnational movements also laid claim to these ideals to press for changes in how states treat their own citizens. Over time their efforts enshrined a view of individual rights as the business of the international community and the domain of international law rather than a matter of strictly internal sovereignty. As the language became global, the rest of the world harnessed and contested human rights ideals in ways that changed Americans’ own aspirations at home and abroad.