Genocide and politicide are recurrent phenomena in modern history, with forty-one cases occurring since 1955. Without a solution to this problem of genocide, this century looks set to be just as bleak as the last. This thesis is a step toward a better understanding of the preconditions and acceleratory factors that allow a civil war to develop into genocide or politicide. It identifies conditions under which governments or rival authorities choose a strategy of genocide during or following civil war. The approach this thesis adopts is that multiple conditions coming from both within and outside the country influence the likelihood that a civil war will develop into genocide. Each precondition, examined by this thesis, is interpreted in terms of its likely effects on authorities’ choices about whether to resort to mass killing in conflict situations. It applies the model to Rwanda and Sudan. This thesis proposes that states commit genocide when they cannot win at war or succeed in a position of power without the destruction of civilian populations. In order to overcome their position of weakness and extend their position of power a state or non-state power resorts to genocide/politicide. The model identifies the enduring characteristics of regimes and societies that are less time dependent, as well acceleratory factors, which have a more immediate effect on the escalation of the violent conflict/political upheaval into genocide.