Scholars have recently reworked the traditional calculus of voting model by adding a term for benefits to others. Although the probability that a single vote affects the outcome of an election is quite small, the number of people who enjoy the benefit when the preferred alternative wins is large. As a result, people who care about benefits to others and who think one of the alternatives makes others better off are more likely to vote. I test the altruism theory of voting in the laboratory by using allocations in a dictator game to reveal the degree to which each subject is concerned about the well-being of others. The main findings suggest that variation in concern for the well-being of others in conjunction with strength of party identification is a significant factor in individual turnout decisions in real world elections. Partisan altruists are much more likely to vote than their nonpartisan or egoist peers.