Long-term thinking and voluntary resource sharing are two distinctive traits ofhuman nature. Across three experiments (N=1,082), I propose a causal connection:Sometimes people are generous because they think about thefuture. Participants were randomly assigned to either focus on the present orthe future and then made specific decisions in hypothetical scenarios. In Study1 (N=200), future-focused participants shared more money in a public dictatorgame than present-focused participants (+39%), and they were willing to donatemore money to charity (+61%). Study 2 (N=410) replicated the positive effect offuture-focus on dictator giving when the choice was framed as public (+36%), butfound no such effect when the choice was framed as private. That is, focusing onthe future made participants more generous only when others would know theiridentity. Study 3 was a high-powered and pre-registered replication of Study 1(N=472), including a few extensions. Once again, future-focused participantsgave more money to charity in a public donation scenario (+40%), and they weremore likely to volunteer for the same charity (+17%). As predicted, the effectwas mediated by reputational concern, indicating that future-orientation canmake people more generous because it also makes them more attuned to the socialconsequences of their choices. Taken together, the results suggest that focusingon the future promotes reputation-based generosity. Bystimulating voluntary resource sharing, a central function of human foresightmight be to support cooperation in groups and society.