Electoral institutions that encourage citizens to vote are widely used around the world. Yet little is known about the effects of such institutions on voter participation and the composition of the electorate. In this paper, I combine a field experiment with a change in Peruvian voting laws to identify the effect of monetary (dis-)incentives on voting. Using the random variation in the fine for abstention and an objective measure of turnout at the individual level, I estimate the elasticity of voting with respect to cost to be -0.21. Consistent with the theoretical model presented, the reduction in turnout induced by the reduction in the fine is driven by voters who (i) are in the center of the political spectrum, (ii) are less interested in politics, and (iii) hold less political information. However, voters who respond to changes in the cost of abstention do not have different preferences for policies than those who vote regardless of the cost. Further, involvement in politics, as measured by the decision to acquire political information, seems to be independent of the level of the fine. Additional results indicate that the reduction in the fine does not affect the incidence of vote buying, but increases the price paid for a vote.Keywords: Voting Behavior; Incentives to Vote, Public Choice, Perú JEL Classification Codes: D71, D72, O53 * I am very grateful to Elisabeth Sadoulet for her patient guidance and advise. Alberto Chong, Michael Conlin, Alain de Janvry, Ernesto Dal Bó, Fred Finan, Francois Gerard, Marco Gonzales-Navarro, Jonas Hjort, Mitch Hoffman, Larry Karp, Valerie Koechlin, David McKenzie, Jeremy Magruder, Ted Miguel, and Gautam Rao provided very insightful comments, suggestions, support, and encouragment. Special thanks to Alex Solís, my officemate, who has patiently heard the contents of this paper at least a thousand times, and always provided smart feedback. Seminar participants at at