Despite the growing interest in direct democratic institutions-like referendums and popular initiatives-the empirical evidence on the relationship between institutional openness and use is still sparse. We use a novel data set on the institutional openness and test its link to actual voting behaviour for ballots in the Swiss cantons for the period 1970-1996. We find no robust relationship between the number of cantonal ballots and openness, measured by the number of signatures necessary to force a ballot and the time limit within which they have to be gathered. We observe, however, that openness is negatively related with voter participation. Having to gather more signatures apparently increases the awareness in the population at large, creates more information about the issues at hand, and thus induces more voters to turn out.