Within the central nervous system, the neuropeptides oxytocin and vasopressin are key regulators of social behavior. While their effects can be nuanced, data suggest that they can influence behavior at multiple levels, including an individual’s personality/temperament, their social interactions in smaller groups (or one-on-one interactions), and their behavior in larger groups. At a mechanistic level, oxytocin and vasopressin help to integrate complex information—including aspects of an animal’s external and internal state—in order to shape behavioral output. Oxytocin and vasopressin help to modulate behaviors that bring animals together (i.e., cooperative behaviors) as well as behaviors that keep animals apart (i.e., competitive behaviors), with the modulatory effects often being species-, sex-, and context-dependent. While there continues to be extensive study of the function of these nonapeptides within individual brain nuclei, over the last two decades behavioral neuroendocrinologists have also made great strides in exploring their roles within larger brain networks that help to regulate social behavior. Looking forward, work on oxytocin and vasopressin will continue to shed light on how the neural regulation of social behaviors are similar, and/or dissimilar, within and between species and sexes, as well as provide insights into the neural chemistry that underlies behavioral differences in neurotypical and neurodivergent individuals.