This article investigates the ways in which political parties are codified in modern democratic constitutions, providing a unique cross-sectional and longitudinal overview of the patterns of party constitutionalization in post-war Europe. Although the constitutions of western liberal democracies traditionally have paid little attention to the role of parties, evidence suggests that in contemporary democracies, both old and new, they are increasingly accorded a formal constitutional status. Little is known, however, about the substantive content of their constitutional position or about the normative connotations of their constitutional codification. In this article, we demonstrate that there is a clear correlation between the nature and the intensity of party constitutionalization and the newness and historical experience of democracy and that, with time, the constitutional regulation of the extra-parliamentary organization and the parties’ rights and duties has gained in importance at the expense of their parliamentary and electoral roles. The analysis furthermore suggests that three distinct models of party constitutionalization can be identified – Defending Democracy, Parties in Public Office, and Parties as Public Utilities – each of which is related to a particular conception of party democracy.