Does religion affect legislative behavior among U.S. senators? Scholars have established this relationship on issues closely associated with evangelical Christianity, but it is unclear how far the relationship extends. Focusing on animal welfare, this article tests the theory of personal representation and provides an expansion of the religion and legislative behavior literature. Humane Society scores (2005–2014) are regressed on senator religion, party, sex, and several constituency factors. The analysis demonstrates that religion shapes animal welfare activity. Relative to mainline Protestant senators, Mormon senators are less supportive of animal welfare, while Catholics, Jews, and black Protestants are more supportive. Some of this is due to senator religion, but it is also a reflection of state‐level factors, including state ideology and religious constituencies.