For some time scholars and policy observers alike have suggested that "artificial," or foreign-drawn borders, are in fact to blame for ethnic conflicts in postcolonial states. So far, however, there has been no empirical evidence to support this assertion. This dissertation's contributions are twofold. First, I provide the first empirical evidence linking foreign-drawn borders with ethnic civil war outbreak, one-sided government violence against civilians, and foreign military intervention. Second, the dissertation provides a refined theory of forced cohabitation as a framework for understanding the relationships between these seemingly unconnected correlations.