This illuminating primary source collection closely examines and analyzes primary documents related to genocidal events from the beginning of the 20th century to the present. Thematically organized into eight sections, each document comes with an introduction and analysis that provides crucial historical background to provide understanding of the complexities of genocide. The first section considers a range of definitional matters relating to genocide, crimes against humanity, and war crimes; subsequent sections examine warnings of impending genocide, and how they have been received; atrocities and how they have been perpetrated; a range of resistance initiatives that have been taken in response to genocide; reactions to genocide from outside actors; the ways in which states have intervened to stop genocide; post-genocide justice measures; and how states and NGOs have sought to prevent genocide.