This article makes a plea for a historical turn in the study of party–state relations. Building on recent insights on the role of political parties in institution-making which have emerged in the historical sciences, it suggests that the deployment of a historical institutionalist perspective can tackle the difficulties in isolating the causal mechanisms and identifying empirical indicators of party–state entanglement, which stand at the foreground of political science studies into the contemporary crisis of democracy in the West. Based on a analysis of institutional reforms of party state relations such as party laws, constitutions, and electoral laws in France, Italy, and Germany over the course of the 20th century, this article demonstrates how, other than the democratic problem which it is considered to be today, the entanglement of party and state not only had long historical roots but also made a major contribution to the democratization of Europe.