Most leading crime theories and crime-control policies are based on the assumption that people are self-interested. But recent work in a variety of fields has challenged this assumption, suggesting that people are both self-interested and socially concerned. Social concern involves biologically based inclinations that sometimes lead people to give more consideration to others than to their own interests. These inclinations include caring about others, forming close ties to and cooperating with others, following certain moral intuitions, and conforming. This article describes the nature of and evidence for social concern, as well as the ways in which social factors shape social concern. The article then presents a theory of social concern and crime. Social concern has direct, indirect, mediating, and conditioning effects on crime. Although social concern generally reduces the likelihood of crime, it has little effect on or increases crime under certain conditions.