This article discusses what role regional organisations can and should play in ensuring implementation of the international Responsibility to Protect (R2P). What formal responsibility and which enabling capabilities do regional organisations have for assuming a role in protecting populations from mass atrocities? The article begins by discussing the formal role projected for regional organisations in the implementation of R2P, individually and vis-à-vis the UN, in the 2005 UN World Summit Outcome Document. The description of this role is then compared to the one depicted in the advisory 2001 report of the International Commission on Intervention and State Sovereignty (ICISS). The second part of the article offers an overview of relevant capabilities held by key regional organisations in Europe, Africa, the Americas, and Asia, capabilities that could enable them to take part in protection tasks prior to, during, or in the aftermath of mass atrocities. In the third part of the report, the capability aspect is seen in relation to the constitutive and constraining impact that individual member states' interests may have on the ability of regional organisations to act within the context of R2P.