This book examines the use of norms by British and Brazilian actors in aid/cooperation in the 21st century, unveiling the politics behind norm circulation. Inspired by a constructivist approach, this research analyses actors’ agency in asymmetric international and domestic environments, in which different norms, dissimilar identities, and opposing interests coexist. Regardless of the discourses and theories surrounding the differentiation between North-South and South-South aid/cooperation, British and Brazilian actors use norms to achieve their own goals at the domestic and international levels. Processes of norm circulation in aid/cooperation have a greater impact at the international level and within the domestic environment of donor/partner countries, than in promoting behavioral changes in recipient countries. However, the content of British and Brazilian norms is different given their historical position in the international architecture and domestic context. The present study sought to unveil the politics behind how actors use aid/cooperation norms in order to achieve their goals in three major instances: 1- the international forums where actors debate the aid/cooperation architecture; 2- the domestic environment of donor/partner countries; and, 3- the domestic level of recipient countries, where international norms are diffused.