The criticism that ordinary voters lack the necessary competence to make policy decisions persists despite the growth, popularity and implementation of direct democratic instruments throughout the democratic world. This article presents a novel measure of voters’ levels of justification as a possible, policy-specific, conceptualization of citizen competence in direct democracy. Using a unique dataset based on thirty-four ballot decisions in Switzerland, the study analyses the levels and correlates of citizen competence. The main findings are, first, that most voters do understand arguments about policies. Secondly, the political context as well as individual resources are important in determining voters’ competence. Finally, with regard to individual resources, motivation is strongly associated with justification levels, while the effect of ability is smaller than expected.