We test the effect of the importance of elections by focusing on turnout at presidential and legislative elections in countries with semi-presidential constitutions. These countries have two potentially first-order elections, but they vary considerably in the powers that are granted to their presidents and prime ministers. We hypothesise that turnout at legislative elections will vary inversely with presidential power and that above a certain degree of presidential power turnout at presidential elections will be higher than turnout at legislative elections. We test these hypotheses on the set of electoral democracies from 1989-2010 inclusive. Controlling for standard social, political and institutional variables, we find strong support for our propositions. The findings show that the importance of the electoral contest is a determining factor for turnout at legislative elections and that the relative importance of presidential and legislative elections can be understood as a continuous scale, and not merely dichotomously.