Elections affect the division of resources in society and are occasions for political elites to make appeals rooted in voters’ self-interest. Hence, elections may erode altruistic norms and cause people to behave more selfishly. We test this intuition using Dictator Games in a lab-in-the-field experiment involving a sample of more than 1,000 individuals in Kenya and Tanzania. We adopt two approaches. First, we experimentally prime participants to think about the upcoming or most recent elections and find that this priming treatment reduces how much money participants are willing to give to other players. Second, we compare results obtained across lab rounds in Kenya taking place right before the country’s 2013 national elections and one eight months prior and find that selfishness is greater in the lab round more proximate to the election. Our results suggest that elections may affect social behavior in important—and previously unrecognized—ways.