East is East and West is West? Comparing Party System Stability in Europe 2008–2019 This article compares trends in party system stability in Central/ Eastern Europe (CEE) and Western Europe, to see if recent studies indicating that the two regions have become more similar hold when the results of outcomes of several post-financial-crisis elections are taken into consideration. Further, it enquires into the underlying causes of electoral volatility and whether they differ between the two regions. In all, 82 parliamentary elections in 25 EU countries 2008–2019 are analyzed as regards electoral volatility (Pedersen’s Index) and support for new parties (‘volatility type A’). The results show that, when the most likely confounding variables are controlled for, a significant difference between the two regions remains, but also that there is a converging trend on both indicators. Moreover, whereas electoral volatility in the West is driven by the level of corruption together with the effective number of parties, unemployment and economic growth as well as the number of effective parties are the main factors explaining the same phenomenon in CEE. There is also evidence that volatility in CEE, unlike in Western Europe, is also driven by a path-dependent logic, where previous volatility scores explain subsequent ones. That finding may have implications for the prospects of future party system stabilization.