We analyze vote buying in Argentina—the payment by political parties of minor benefits (food, clothing, cash) to citizens in exchange for their votes. How widespread is vote buying in Argentina, and what is the profile of the typical vote "seller"? Did the shift toward a neoliberal economic model in the 1990s increase or reduce vote buying? Why do parties attempt to buy votes when the ballot is secret and people could simply accept campaign handouts and then vote as they wish? We analyze responses to surveys we conducted in Argentina in 2002 and offer answers to these questions. Our findings suggest that vote buying is an effective strategy for mobilizing electoral support among low-income people when parties are able to monitor voters' actions, make reasonably accurate inferences about how individuals voted, and credibly threaten to punish voters who defect from the implicit clientelist bargain. Our results point toward ballot reform as one way to reduce vote buying in Argentina.