Party fission is a relatively frequent phenomenon in many established and new democracies. However, the comparative politics literature does not provide a systematic account of the effect of fission on party systems. This paper seeks to fill this gap by studying how votes are redistributed between successor parties after a split. For example, when do the supporters of the “parent” party continue to vote for it even after it splits, when do they shift their support to a splinter party and when do they switch to third parties? In order to answer these questions, the study will test hypotheses derived from spatial, sociological and strategic theories of voting behaviour. These hypotheses will be tested using the statistical analysis of party and electoral data from 24 established and newer European democracies in the post-war period. The research will make an important contribution to the knowledge on party system change and voter behaviour.
