Research across species has shown that the neuropeptide oxytocin plays a key role in the regulation of social cognition and behavior. It is important for attachment, social exploration, and social recognition, as well as anxiety and stress-related behaviors. Based on oxytocin administration studies and measurements of peripheral oxytocin levels, it has been suggested that signaling of oxytocin is impaired in mental disorders associated with social deficits, including autism, borderline personality disorder, and social anxiety disorder. There are several factors influencing interindividual differences in social-cognitive abilities and differences in the susceptibility to psychiatric disorders, including variability in genes involved in oxytocin signaling. In addition to sequence variation, interindividual differences might in part be explained by variation in epigenetic processes influencing gene expression. Here, we provide an overview of the functional organization and epigenetic regulation of the murine and human oxytocin receptor gene.