We report the results of a randomized field experiment in the Philippines on the effects of two common anti-vote-selling strategies involving eliciting promises from voters. An invitation to promise not to vote-sell is taken up by most respondents, reduces vote-selling, and has a larger effect in races with smaller vote-buying payments. The treatment reduces vote-selling in the smallest-stakes election by 10.9 percentage points. Inviting voters to promise to “vote your conscience” despite accepting money is significantly less effective. The results are consistent with a behavioral model in which voters are only partially sophisticated about their vote-selling temptation.