The demand for organ transplants far exceeds supply. Underlying this shortfall is the fact that some people choose to register as organ donors, whereas many others decide not to. Why do people vary in their attitudes and choices regarding organ donation? We hypothesize that attitudes toward organ donation and decisions to register as a donor are linked to prosociality. We test this hypothesis across two studies, both of which suggest that prosociality is linked to attitudes toward organ donation or actual donor status. Study 1 demonstrates that two groups (economics students and psychology students) that have previously been shown to differ in prosocial orientations have different attitudes toward organ donation and are registered as organ donors at different rates. Study 2 investigated three groups (economics, psychology, and medical students), and it found that messages framing organ donation as a prosocial act affect willingness to become a donor, but only among economics students and among students who score lower on an instrument designed to measure prosociality. Implications and future research directions are offered.