Roll-call votes are important tools for legislative studies. They serve as an empirical foundation for many insights about the causes of party unity and the dominant lines of political conflict. In light of their importance surprisingly little is known about the causes behind the varying frequency of recorded votes across parliaments. This article presents a comprehensive model explaining the different supply of recorded votes as a function of their saliency in the political competition between goal-seeking party groups. Drawing on an original dataset covering 109 electoral terms of all 16 sub-national parliaments in Germany (Landtage) the influence of different variables on the frequency of recorded votes is tested. The results show a significant impact of the electoral system, political polarisation, the presence of 'outsider' parties in the legislature, the margin of the government's majority and voting technology.