Combining the methods of neuroscience and economics generates powerful tools for studying the brain processes behind human social interaction. We argue that hedonic interpretations of theories of social preferences provide a useful framework that generates interesting predictions and helps interpret brain activations involved in altruistic, fair and trusting behaviors. These behaviors are consistently associated with activation in reward-related brain areas, such as the striatum, and with prefrontal activity implicated in cognitive control, the processing of emotions, and integration of benefits and costs, consistent with resolution of a conflict between self-interest and other-regarding motives.