The end of the Cold War was followed by an increase in the influence of ethnonational conflicts in the world politics. International Relations theories have contributed to the study of inter-state war. The question raised in this dissertation is whether the same logic can be used to study ethno-national conflict. To answer the question this dissertation evaluates the contribution of traditional International Relations theories, post-Cold War approaches and Constructivism to our understanding of ethno-national conflict. It points to their strengths and weaknesses in explaining this conflict. The Kosovo/a conflict is used as a case study to illustrate to what extent different International Relations approaches help us to understand it. This dissertation asserts that traditional theories and post-Cold War approaches help us to examine the context that would encourage conflict. Pointing to the limits of these approaches, this dissertation emphasizes the contribution of Constructivist approaches, which assist us to understand the constructive and relational processes which make the conflict and shape the participants. At the same time, this dissertation shows awareness of Constructivism weaknesses.