The end of the Cold War led to the creation of almost two dozen new states, resulting from groups that advanced claims based on the legitimacy of national self-determination. These claims ranged from modestly increased autonomy to secession and independent statehood. As a result, and because a number of these claims escalated to violence, scholarly research into self-determination and secession has increased tremendously over the past two decades, with scholars examining the fate of these movements and associated violence and wars, from onset to the termination of associated violence and wars. This article assesses the state of the academic literature as it relates to the links between self-determination, secession, and civil wars. It begins with a discussion of what exactly is understood by such key concepts as ethnicity, self-determination, secession, and secessionist war. It then turns to the conditions and factors that have been identified in the literature to explain the emergence of self-determination and secession and why violence and war become potential outcomes. [Supplemental materials are available for this article. Go to the publisher's online edition of Terrorism and Political Violence for the following free supplemental resource: article appendix of ethic groups at political risk, list of territorial secessionist wars, and militant secessionist groups active in the last 25 years.]