On July 12th, 1990 the Serb Democratic Party of Bosnia-Herzegovina (SDS BiH) held its founding assembly. Less than five months later, it participated in the November 1990 elections in Bosnia-Herzegovina (BiH), winning a decisive majority of the vote of ethnic Serbs. Yet, SDS BiH was not an ordinary political party. In the sixteen months that followed the elections, it initiated a series of activities that eroded the power of BiH institutions to which it had been elected. SDS BiH declared its own organs superior to those of BiH and established exclusive control in Serb-majority areas. In early 1992, it united these areas into a single Serb Republic, formed an exclusively Serb armed force, and set out to violently expand the territory that would be incorporated into the new statelet. This study seeks to advance an understanding of the role of ethno-nationalist agents in the outbreak of violent conflicts fought in the name of ethnic nations by analyzing the activities of SDS BiH on the political homogenization of Serbs in the two years leading up to the 1992 onset of violence in BiH. It incorporates the tools of discourse analysis and the recent findings in the studies of human cognition, identifying the agency of SDS BiH in the power of the Party's discourse to produce affective sensibilities that served its nationalist agenda. It argues that this engineering of affect was crucial for constituting the dispersed individuals of Serb ethnic background as a palpable political group, and preparing them for armed mobilization. The analysis also argues that ethno-nationalist agency can be properly understood only by considering the case-specific structural factors with which all agents interact. Toward this point, it draws contrast between the agency of SDS BiH and that of the National Movement in the Republic of Georgia, showing that ethnic structures hold a greater explanatory value in the Georgian case. Rather than departing from pre-given ethnic groups, both case studies suggest that conflict analyses should problematize the dynamic interaction between the dominant ethno-nationalist agents and ethnic structures, which produce ethnic groups, ethnic interests and sides to armed conflicts. / Ph. D.