The literature documents that charitable giving is responsive to tax subsidies but often ignores the spillover effects of such policies. This paper investigates the spillover effects of charitable subsidies on religious participation using individual-level panel data. The results show that religious giving and participation are complements. The implied cross-price elasticity of religious participation with respect to the after-tax price of giving is −0.27. Furthermore, a 1% increase in the amount of religious contributions is associated with a 0.4% increase in religious attendance. These results are robust under several different specifications and highlight the positive externalities created by charitable subsidies.