This paper argues that Latin American Catholic Action played a hitherto underappreciated role in the creation of a truly global human rights movement amid the wave of repression by right-wing military dictatorships in Latin America. Scholars such as Samuel Moyn (2012) have argued that human rights only acquired international relevance in the 1970s when organisations like Amnesty International (AI) gained prominence. Yet, while Kathryn Sikkink (2018) and others have noted the importance of Latin America, these works have generally neglected the role that transnational Catholic networks played at this crucial juncture. The persecution of Catholic Youth Workers (JOC, Juventud Obrera Católica) activists who suffered from imprisonment, torture, and in some cases, murder or disappearance by security forces employed by these dictatorships is well-documented. Here, this paper draws on Catholic archives in Latin America, North America, and Europe as well as from Amnesty International's collections to show how the JOC contributed to the documentation of human rights abuses in the Southern Cone in the 1970s. As it demonstrates, the persecution of JOC militants led its international bureau to embrace and promote human rights to not only defend itself, but through its practical collaboration with Amnesty International and related human rights organisations.