In my dissertation, entitled Breaking-Up Is Hard To Do: Secession and State Formation (1815-2010), I ask: Why are some secessionist movements that fight for statehood are recognized as states while others are not? There are two prevalent explanations for this phenomenon. One takes a domestic perspective, arguing that successful secessions are determined by specific domestic factors inherent to the secessionist movement; geography, population, party systems, and economic prosperity. The second explanation argues from an international perspective, claiming that statehood is a product of external recognition that is determined by international relationships and not domestic conditions. In addition, this perspective views politically motivated self-interest by existing major powers in the international system as driving the recognition of seceding territories. I argue that these prevalent explanations do not account for normative factors associated with democracy and material factors associated with great power involvement. To test my argument, I utilize a mixed-methods approach consisting of quantitative and qualitative components. The quantitative component uses a large-n dataset consisting of secessionist conflicts that occurred from 1815-2010. The data comes from a variety of sources, which are listed in the appendix of my dissertation, but the majority of the data was collected from two sources; the Minorities at Risk data project and the Correlates of War data project. The qualitative component consists of case-studies from the break-up of Yugoslavia. These cases are selected to account for how (or if) norms diffuse in the international system over time. Selecting cases that are similar except for the variables of interest (norms of self-determination and liberal democracy, strength of secessionist movement, and proximity to major powers or contiguous rivals) allows me to explain in detail the causal mechanism that leads violent secessionist movements to become recognized as new states in the international system.