This article examines the role that groups played in the rise of Responsibility to Protect (R2P) within the United Nations (UN) system. It focuses in particular on the role of informal groups of states in advancing a consensus on R2P, contrasting their role with that of formal regional and political groups, which — with the exception of the African Group — played a more marginal role. R2P has given rise to a multiplicity of informal groups of states. These informal groups operate alongside the formal regional and political groups and, with one or two exceptions, have tended to be significantly more influential, the main reason being the principle’s genesis. Arising out of fractious debates in the late 1990s about intervention and the relationship between sovereignty and fundamental human rights, R2P was from the outset a conscious attempt to bridge political divides between states in the UN — especially the ‘North–South’ theatre.