The concept of religious tithing - giving 10% or more of one's income to religious organizations - permeates ancient and contemporary religious literature. Yet, the degree to which households apply this construct in their charitable giving practices remains unclear. This study examines the practice of tithing using data from a national expenditures survey including 56 663 households. Despite the pervasiveness of the tithing concept, religious donors did not appear to be targeting a specific 10% giving level. This may have resulted from varied definitions of income for tithing purposes or the presence of small charitable gifts made without reference to income. While the likelihood of religious giving increased with income, the likelihood of tithing fell dramatically. As a group, tithers had less income, but were wealthier, more educated, older and gave more to nonreligious charity than did other households. Religious tithers who also gave to nonreligious charities were wealthier, older and more highly educated than tithers who gave only to religious organizations.