This chapter outlines the NGO sector’s transformation from a vector for traditional ideas of charity, welfare and disaster relief, to the more expansive ‘NGO movement’, equally concerned with matters of human rights, economic equality and global justice, that it became. The emergence of a new generation of aid workers in the late 1960s and early 1970s is at the heart of this narrative. What challenges, the chapter asks, did these individuals pose to how NGOs thought about aid? And how did the sector adapt to these changes? To answer those questions, the chapter explores how left-wing critiques of aid, the influence of intellectuals like Paulo Freire, Ivan Illich and Argentinian economist Raúl Prebisch, and a new emphasis on poverty and inequality in transnational religious circles, converged in a common discourse that placed ‘justice’ (broadly defined). The emphasis on reform in those discussions was key. Ultimately, this story is one of compromise, of how ideas of advocacy and reform were absorbed and rearticulated by the NGO sector.