Social disability represents a unifying feature in the diverse group of individuals with autism spectrum disorder (ASD). Social neuroscience is the study of brain mechanisms supporting interpersonal interaction. In this paper, we review brain imaging studies of the social brain and highlight practical applications of these scientific insights. Understanding of social brain mechanisms holds promise as a tool for defining meaningful subgroups of children with ASD to facilitate genetic analyses and to inform treatment selection. Because social brain systems emerge in infancy, social neuroscience may help to detect atypical development before symptoms manifest. This conceptualization of ASD is a hopeful one, as social brain systems remain malleable well into development and are thus amenable to targeted intervention.