Past research argues that religious commitments shape individuals’ prosocial sentiments, including their generosity and solidarity. But what drives the prosociality of less religious people? Three studies tested the hypothesis that, with fewer religious expectations of prosociality, less religious individuals’ levels of compassion will play a larger role in their prosocial tendencies. In Study 1, religiosity moderated the relationship between trait compassion and prosocial behavior such that compassion was more critical to the generosity of less religious people. In Study 2, a compassion induction increased generosity among less religious individuals but not among more religious individuals. In Study 3, state feelings of compassion predicted increased generosity across a variety of economic tasks for less religious individuals but not among more religious individuals. These results suggest that the prosociality of less religious individuals is driven to a greater extent by levels of compassion than is the prosociality of the more religious.