This paper re-evaluates the party system change in Turkey based on Sartori’s framework. It also explores the role of opposition parties in this. The paper suggests that, while a fragmented opposition may lead to the emergence of a one-party government and/or military intervention because of the high levels of polarization it induces, bilateral opposition prolongs one-party governments. The paper relies on an analysis of party programs and public opinion surveys in order to position the parties in terms of spatial distance and to understand the level of polarization.