The article deals with the potential impact of the electoral system on the party system. The general discussion, based on Duverger’s and Sartori’s electoral rules, concludes with an assessment of the Austrian case. Austrian party system development is examined with regard to the evolution of the country’s proportional representation electoral system. The author tries to find more relevant explanations for the changes within the Austrian party system’s logic of functioning other than the electoral system, such as the de-alignment of voters and the changing structure of cleavages. In order to show another factor shaping the Austrian party system arrangement, the author tries to discuss not only recent development since the mid 1980s, but he also evaluates the Austrian First Republic and the period from 1945 to 1986 . The article concludes with the argument that Duverger’s and Sartori’s electoral rules could be useful in discussing party system format but they have very little to say when party system mechanics is concerned.