Abstract This article aims to integrate existing theories on parties and political systems with the literature on party funding. On an empirical level, it asks why the German system of party funding developed in the way that it did. Germany combines a system of high transparency levels for political parties with generous state funding. Taking actor?centred institutionalism as a starting point, three variables are identified which explain the evolution of party funding regimes: the number of veto points available to opposition parties, parties? dominant goals during decisions on reforms of funding regulation, and the public discourse on political corruption. Reforms of party funding regimes are assumed to become more probable (1) the more institutional veto points even opposition parties have at their disposal, (2) the lesser the influence of vote?seeking strategies among parties, and (3) the more intense the societal discourse on political corruption. These hypotheses find support from the German case and may therefore be able to explain the convergence of western European party funding regimes around state subventions and transparency obligations.