An important agenda power in parliamentary democracies is the discretion over the dissolution of parliament. We argue that variation in constitutional rules and the political environment will systematically affect the frequency of early elections. We hypothesize that dissolution will be more frequent under single-party governments, when the head of state plays an insignificant role, when neither parliament nor the cabinet can inhibit dissolution, when minority governments are in power, when the head of state can dissolve unilaterally, and later in the constitutional term. Using standard logistic and Cox-proportional hazard techniques, we test these expectations in a pooled time-series setting against observations of most OECD parliamentary democracies for the years 1960–1995. We find that parliamentary dissolutions are more frequent earlier in the constitutional term, under minority governments, when the head of state plays an insignificant role, and when the parliament or the cabinet is not involved.