The idea of self-determination is one of the most significant in modern international politics. For more than a century diplomats, lawyers, scholars, activists, and ordinary people in every part of the globe have wrestled with its meaning and implications for decolonization, human rights, sovereignty, and international order. The First Right argues that there was no one self-determination, but a century-long contest between contending visions of sovereignty and rights that were as varied and changing as the nature of sovereignty itself. In this globe-spanning narrative, Simpson argues that self-determination's meaning has often emerged not just from the United Nations but from the claims of movements and peoples on the margins of international society. Powerful states, he shows, persistently rejected expansive self-determination claims, arguing that these threatened great power conflict, the dissolution of international order, or the unravelling of the world economy. Pacific Island territories, indigenous peoples, regional and secessionist movements, and transnational solidarity groups, among others, rejected the efforts of large, powerful states to define self-determination along narrow lines. Instead, international historian Bradley R. Simpson shows they offered expansive visions of economic, political, and cultural sovereignty ranging far beyond the movement for decolonization with which they are often associated. As they did so, these movements and groups helped to vernacularize self-determination as a language of social justice and rights for people around the world. An ambitious work of global breadth on a key geopolitical issue, The First Right transforms how we think about the making of the twentieth century world order and the place of the global South and decolonization in it.