 With co-authors, he has also explained the rise of the new radical right parties in Europe, in light of this shift and studied the formation of party systems in post-communist democracies.In respect to Eastern Europe, Kitschelt argues that patterns of party competition in post-communist states - and the extent to which they are structured in programmatic (as opposed to clientelistic) terms- are produced by legacies of different forms of communist rule, which in turn reflect pre-communist social and state structures.Kitschelt and his co-authors accept, however, that institutional arrangements will start to gain importance over time and may be crucial in strengthening the process of party system development.