The core focus of the project is on the influence of European party federations ("Europarties") on their Central and Eastern European partner parties and their party systems. As a "process within the process" the Eastern enlargement of the European party families occurs within the general Eastern enlargement of the European Union. European party families consist of three components: the national parties, the group in the European parliament and the (extra-parliamentary) Europarty. For structural reasons, Europarties are best suited for the practical accomplishment of Eastern enlargement of European party families. In this process, they search for Central and Eastern European partner parties on which they try to exert influence ("West-Europeanization"). These influences may also affect the relevant national party systems. Despite some notes in the literature, previous analyses show neither how influence is exercised nor which impact it really has on Central and Eastern European parties and party systems. This project aims at filling this research gap by carrying out a comprehensive and systematic empirical analysis of the impact of Europarties on their Hungarian, Slovakian and Romanian counterparts. In addition, the results can also help to shed some light on the more general question as to how much influence external actors may have on developments in young democracies.