This article explores the origins of the UN's commitment to human rights and links this to the wartime decision to abandon the interwar system of an international regime for the protection of minority rights. After 1918, the League of Nations developed a comprehensive machinery for guaranteeing the national minorities of eastern Europe. But by 1940 the League's policies were widely regarded as a failure and the coalition of forces which had supported them after the First World War had disintegrated. German abuse of the system after 1933, and the Third Reich's use of ethnic German groups as fifth columns to undermine the Versailles settlement were cited by east European politicians as sufficient justification for a new approach which would combine mass expulsion, on the one hand, with a new international doctrine of individual human rights on the other. The Great Powers supported this because they thereby escaped the specific commitments which the previous arrangements had imposed on them, and which Russian control over post-war eastern Europe rendered no longer practicable. But they also supported it because the new rights regime had no binding legal force. In respect, therefore, of the degree to which the principle of absolute state sovereignty was threatened by these arrangements, the rights regime of the new UN represented a considerable weakening of international will compared with the interwar League. But acquiescing in a weaker international organization was probably the price necessary for US and Soviet participation.