This paper argues that the integration of Europe through immigration, trade, and integration may mark a critical juncture in the political development of Europe, comparable to the previous shifts identified by Lipset and Rokkan. The authors present evidence suggesting that party systems are shaped by episodic breaks from the past, political parties are inflexible in their programmatic commitments, and as a result, party system change occurs through the rise of new parties. The emergence of a transnational cleavage, centered on opposition to European integration and immigration, is discussed as a significant structural conflict in Europe. This cleavage is driven by social forces and has led to the rise of radical right parties in some countries, such as Germany, and the rejection of EU membership in the UK referendum. The paper also examines the impact of economic and migration crises on party systems, finding that mainstream parties have remained stable while voters have changed their preferences. The authors conclude that the crises have revealed the disruptive nature of party system change, driven by new social divisions and constrained by the policy commitments and reputations of established parties.This paper argues that the integration of Europe through immigration, trade, and integration may mark a critical juncture in the political development of Europe, comparable to the previous shifts identified by Lipset and Rokkan. The authors present evidence suggesting that party systems are shaped by episodic breaks from the past, political parties are inflexible in their programmatic commitments, and as a result, party system change occurs through the rise of new parties. The emergence of a transnational cleavage, centered on opposition to European integration and immigration, is discussed as a significant structural conflict in Europe. This cleavage is driven by social forces and has led to the rise of radical right parties in some countries, such as Germany, and the rejection of EU membership in the UK referendum. The paper also examines the impact of economic and migration crises on party systems, finding that mainstream parties have remained stable while voters have changed their preferences. The authors conclude that the crises have revealed the disruptive nature of party system change, driven by new social divisions and constrained by the policy commitments and reputations of established parties.