The process of splinter party formation has been understudied. This is related with the difficulties in studying the intraparty realm of politics and the inability of the splinter parties to turn into successful competitors. Employing an actor-oriented approach, this study traces the reasons behind splits in mainstream parties and formation of splinter parties. It intends to develop a theoretical model for explaining party splits in Turkey. It is asserted that party split is one of the possible outcomes of the competition between the dissenting faction and the dominant faction supporting the party leader. This outcome is preceded by two stages: dissent, and intraparty conflict. Strategies developed by dissenting faction and the party leader’s response are conditioned by a number of endogenous and exogenous factors. Endogenous factors include the nature of disagreement, relative power of competing factions across the different layers of party organization and leadership autonomy. Exogenous factors include the costs of forming a new party and the perceived viability for a new party. Splinter party is formed in case the dissident faction that departs from the parent organization chooses to invest on a new party rather than switching to an established party. The model proposed in this dissertation is illustrated by a comparative analysis of five cases of party splits in Turkish party system since the transition to democracy in 1946. The political parties that are analyzed within the scope of this study include the Democrat Party, the Republican People’s Party, the Justice Party, the True Path Party and the Democratic Left Party. The analysis reveals that endogenous factors are more influential over party splits compared to the exogenous factors. Moreover, in case the dissidents are unlikely to voice within the party platforms, they might simply resign without voice.