This dissertation attempts to explain the variation in violence at the time of state secession. Why do some governments respond to secessionist demands with violence and others settle such disputes peacefully? Previous research emphasized the high value of the secessionist region, the state’s fear of a domino effect, and the political fragmentation of the state and secessionist region elites, as the primary explanations for the violent response of the state to secession. I seek to provide a more comprehensive theory for the variation of secessionist violence that integrates individual, regional, state, and international factors. Drawing on a rational choice approach, and recent research on dehumanization, I argue that the state’s response to secessionist claims depends on the degree of economic redistribution in the country, the cultural differential between the dominant group of the state and the secessionist group, and the international security of the state. My theory predicts that the state is less likely to use violence against secessionists when there is a high degree of economic redistribution, a small cultural difference between the dominant and secessionist group, and the state enjoys a high level of external security. A state willing to redistribute in favor of the secessionist region dampens support for secession in the region and reduces the need to use violence by the state. Due to cognitive biases of the human brain, it is easier to marginalize culturally distinct groups than culturally similar groups. As a result, a high cultural differential is often associated with greater probability of secessionist violence. When the international security of the state is under threat, the government of the state can more easily convince its population to use force against the secessionist region, regardless of other considerations. In sum, my theory implies that economic redistribution, cultural differences, and international security shape state responses to secessionist claims. I test these theoretical conjectures using a new dataset on peaceful and violent secessionist campaigns, along with several case studies based on field research and primary source materials and find strong supportive evidence for them.