Abstract How can one explain the significant vote losses of mainstream parties across Europe in recent years? In this article, it is argued that mainstream party convergence is an important determinant of the recent political and electoral volatility in European party systems. More specifically, it is hypothesised that as mainstream parties converge on the left‐right scale, voters will switch from supporting a mainstream party to a non‐mainstream party in the next election as they look for an alternative that better represents their ideological views. To test these theoretical expectations, data is combined from the Comparative Study of Electoral Systems and the Manifestos Project for nearly 15,000 vote choices of individual voters in 30 elections in 16 West and East European countries from 2001 until 2013. The findings have important implications for understanding the recent rise of non‐mainstream parties, the changing nature of party systems and the increasing complexity of cabinet formation across Europe.