Despite its prevalence, little is known about when parties buy turnout. We emphasize the problem of parties monitoring local brokers with incentives to shirk. Our model suggests that parties extract greater turnout buying effort from their brokers where they can better monitor broker performance and where favorable voters would not otherwise turn out. Exploiting exogenous variation in the number of polling stationsâ€”and thus electoral information about broker performanceâ€”in Mexican electoral precincts, we find that greater monitoring capacity increases turnout and votes for the National Action Party (PAN) and the Institutional Revolutionary Party (PRI). Consistent with our theoretical predictions, the effect of monitoring capacity on PRI votes varies nonlinearly with the distance of voters to the polling station: it first increases because rural votersâ€”facing larger costs of votingâ€”generally favor the PRI, before declining as the cost of incentivizing brokers increases. This nonlinearity is not present for the PAN, who stand to gain less from mobilizing rural voters.