Ten years ago, the UN General Assembly officially adopted a collective responsibility of the international community and each individual member State to prevent mass atrocities – the Responsibility to Protect (R2P). R2P is a set of moral norms intended to protect populations in all countries against genocide and other mass atrocity crimes. Individual norms within the R2P, such as the responsibility of the international community to respond to such crimes, are highly controversial and have incited intense disagreement in the past. Have these controversies weakened or strengthened the R2P doctrine? How far has institutionalization of the responsibility to protect advanced? In this report, Gregor P. Hofmann analyzes the degree to which R2P has been acknowledged by states and draws attention to possibilities for its further development on an international scale. Gregor P. Hofmann is a research associate in the International Security and World Order research department of the Peace Research Institute Frankfurt. His research focuses on international R2P, the development of international norms, and the role of notions of justice in international negotiations.