This paper analyzes optimal taxation of charitable giving to a public good in a Mirrleesianframework with social comparisons. When there are no transaction costs of giving, charitablegiving should be subsidized to such an extent that government contributions are completelycrowded out, regardless of whether the government is welfarist or non-welfarist, in whichcase it does not acknowledge the warm glow of giving. Under welfarism, stronger concernsfor relative charitable giving support lower marginal subsidies, whereas relative consumptionconcerns work in the opposite direction. We also show that a simple flat-rate subsidy isoptimal under welfarism, while the marginal subsidy increases in income under nonwelfarism.