Based on quantitative analysis of a nationally representative sample of 1,589 self-reported eligible blood donors in the United States, this paper investigates how religion influences giving the gift of life. I find significant positive effects for both organizational and subjective dimensions of religion. The reasons these dimensions promote this generous act vary, however. Religious service attendance works entirely through religious ties. These ties, in turn, influence various established channels of donation, including solicitation to donate, which not only has a direct effect on giving, but also indirect effects through moral norms and willingness to donate. In addition to its impact on these ties, religious group involvement encourages blood donation through exposure to messages about helping others. Finally, the impact of religious salience operates through the belief that "it is better to give than to receive" as well as religious ties. The implications of these findings for both the literature on blood donation and the larger scholarship on religion and generosity are discussed.