During the conflict and war in Croatia and Bosnia, Serb leaders frequently emphasised the need for unity; the need for homogeneity in the face of impending challenges. However, disunity and rivalry prevailed among the Serb leaders and only became more acute as the conflict intensified. This intra-Serb competition has received little attention in the literature on the Yugoslav conflict and competition within groups is furthermore under-analysed in the theoretical literature on ethnic conflicts. But intra-ethnic competition significantly affects the positions adopted by ethnic leaders and parties, and an examination of these dynamics is therefore important for the study of ethnic conflicts and wars. Through an in-depth analysis of intra-Serb elite rivalry in Croatia and Bosnia, this thesis explores the impact of intra-ethnic competition. It argues that intra-Serb competition constituted a significant independent dynamic in the Yugoslav conflict and without it one cannot fully understand the escalation of the conflict, the outbreak of war and the continuous rejection of peace settlements. The Serbian regime played a significant role through the supply of resources, but the thesis will find that Slobodan Milosevi? was not always able to control the local Serb leaders. The victory of hardliners was the prevalent, but not the only, dynamic in the intra-Serb competition. Hardline dominance was generally contingent on the control of economic and coercive resources, and not based on appeals to popular sentiments; it was not about elites successfully 'playing the ethnic card'. Based on these findings a preliminary theory of the impact of intra-ethnic competition in inter-ethnic conflict will be suggested. As a corrective to existing theorising, it will argue that intra-ethnic competition does not necessarily lead to radicalisation, not even in a situation of war and polarisation. Popular support is, moreover, not the only resource of importance for the competing elites and radicalisation need not be driven by popular demands