The tragic events during the 1990s in Rwanda, Srebrenica, and Kosovo, as well as the recent crisis in Libya, have triggered a fundamental rethinking of the role and responsibility of the international community in regard to mass atrocities. The principle of the Responsibility to Protect maintains that although individual nations bear the brunt of the responsibility to guard against genocide, ethnic cleaning, and crimes against humanity within their boundaries, the international community must step in when the state is unable or unwilling to provide such protection. This book assesses to what extent the principle is grounded in international law and examines how international institutions, including the United Nations, can contribute to the aim of protecting victims in cases of mass atrocities.