We study the effects of compulsory civic duty on turnout. We take advantage of a natural experiment provided by the fact that in Spain there is a lottery to select individuals that will act as electoral officers on the election day. Being an electoral officer is compulsory. We study whether acting as an officer changes turnout in subsequent elections and attitudes about democracy and elections. We find that compulsory civic duty has a strong short-term and positive effect on electoral participation but has no effect on political attitudes. This is consistent with psychological theories that argue that exposure to certain treatments activate behaviors consistent with individuals' underlying values without changing those values. Interestingly the positive effect of the civic duty treatment fades very quickly. The absence of long run effects questions existing theories about civic duty and the formation of political habits.