The last third of the twentieth century witnessed an unprecedented global convergence on the use of human rights as a moral and political framework for a wide variety of state and non-state actors. My dissertation investigates this advent of a transnational politics of human rights in the “long 1970s,” when social activists raised global awareness about rights abuses during military dictatorships in Brazil, Chile, and Argentina. At the core of my work is an effort to understand the ideological and political negotiations of local activists in South America and NGOs such as Amnesty International over the concept of human rights. Utilizing an interdisciplinary and transnational methodology, I draw from archives in South America, Europe, and the United States, as well as oral testimonies with activists from this period. In focusing on the explicit idiom of human rights, I will trace the evolution of human rights activism from its embryonic form in the late 1960s, through its explosion after the Chilean coup of 1973, to the development of an international human rights regime by the time of the 1976 Argentine coup. Through these campaigns, my research foregrounds the shared contributions and rival visions of transnational activists who first used the language of human rights in a sustained way. My work also speaks to enduring dilemmas for human rights politics in Latin America and beyond. When human rights emerged in the 1970s they were seen as an appealing form of anti-politics, a minimalist utopia, and a frantic response to political emergency. Yet, as human rights politics snowballed over the next few decades, its program expanded far beyond its initial breakthrough as a response to catastrophe to offer a universal vision of utopian politics. My project thus seeks to explain a paradox of human rights as it cascaded through the end of the twentieth century: the essential tension between human rights as an anti-political language that is necessarily political.