Party system institutionalization has been traditionally viewed as a necessary, but not sufficient, condition for the healthy functioning of democracy. Mainwaring summarizes the common agreement among scholars when he states that "democracy is likely to have shortcoming if a moderately institutionalized party system does not emerge after democratic government has been inplace for some time" (1999:6). However, there has been far less agreement in the literature about what it is that institutionalizes party systems in the first place. In fact, comparative political theory has offered up to sixteen different explanations for the distinct levels of institutionalization observed among new democracies in different regions of the world. Trying to put some order within such "totus revolutus", this paper provides an analysis of the determinants of party system institutionalization (or not) in 16 new post-communist democracies (i.e. Albania, Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Macedonia, Moldova, Poland, Romania, Serbia, Slovakia, Slovenia and Ukraine) on the basis of a combination of qualitative comparative analysis and case-studies. The main finding of the paper is a set of factors (and their mechanisms) which jointly have contributed to the institutionalization of party systems in some countries, while in others not.
