Clinical observations and research in human and nonhuman primates show clearly that nurturing received during infancy and childhood influences the quality of parental and other social behaviors as well as the ability to cope with stress during adulthood. Analogous effects of early nurturing on adult outcomes have been demonstrated in rodents in recent years. This chapter summarizes the numerous ways in which the neuropeptide oxytocin (OT) contributes to mothers' developmental effects on their daughters. Earlier studies found that disruptions of central OT inhibited the onset of all components of maternal behavior in parturient or ovarian steroid-treated female rats but did not appear to affect established mothering behavior. By making numerous observations, it is demonstrated that OT selectively enhances frequencies of the pup-licking (PL) and kyphotic nursing (KN) components of well-established maternal behavior in lactating rats as well as the PL component of spontaneous maternal behavior in nulliparous C57BL/J6 mice. Among the strongest findings is that central OT contributes to as much as 40% of mothers' PL and KN frequencies, those components of maternal behavior that exert the greatest developmental effects on their daughters. The amount of PL and KN received during the early postnatal period appears to determine the degree to which OT facilitates these components of maternal behavior in adult daughters possibly by influencing how much OT binding is upregulated in daughters' brains by rising estrogen levels during late pregnancy.