The neuropeptides oxytocin and vasopressin play important roles in several aspects of social cognition and behavior in animal models, including social recognition, maternal nurturing and social bonding. Several studies suggest that these neuropeptides increase the saliency of social stimuli, enhancing the neural processing of social cues. A series of studies in voles demonstrate that variation in oxytocin and vasopressin receptor systems contributes to both species differences and individual variation in social behavior. Oxytocin and vasopressin receptor activation in the mesolimbic dopamine reward pathway plays an important role in social bond formation. We have identified genetic polymorphisms that robustly predict neuropeptide receptor expression in the brain, which in turn predicts social behaviors, including susceptibility to the impact of early social stressors on later life social attachment. There are remarkable parallels between those studies in voles and recent studies in humans which suggest that these mechanisms are highly conserved from rodent to man. In humans, intranasal delivery of oxytocin enhances eye gaze into the eyes of other, the ability to infer the emotions of others from facial cues, empathy, and socially reinforced learning. These observations suggest that the oxytocin system may be a viable target for novel pharmacological strategies for improving social cognition in autism spectrum disorders. Drugs that stimulate endogenous oxytocin release may be useful as an adjunct therapy for behavioral interventions for autism.