Why are some states more corrupt than others? Drawing on the literature on governance in parliamentary democracies, we suggest that the degree of corruption depends on the ability of key political actors to control ministers who have been delegated power. We argue that the Prime Minister has incentives to limit corruption within the cabinet and has the ability to do so when there are certain "control mechanisms" at hand. One such mechanism is the PM's ability to fire or demote ministers who are not behaving in accordance with his or her wishes. We hypothesize that governmental corruption will be lower in systems where the constitution grants the PM strong powers. Using a new dataset (Varieties of Democracy), which provides more specific measures on high-level corruption across a longer time period, we analyze corruption in 26 West and East European democracies over the post-war period and find support for our hypothesis.