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Oxytocin is known to be positively correlated with social behavior in many mammalian species, including humans and rodents. However, little is known of the effects of oxytocin early in life and how early exposure may affect later social development. In semi-altricial and altricial neonates, social behavior is limited to auditory distress signals. Human infants solicit parental care by crying, while neonatal mice emit ultrasonic calls that serve a clear functional purpose as they trigger a dam’s retrieval response. In the present experiment, oxytocin and oxytocin with antagonist were subcutaneously administered to mouse pups between P8-9. Following drug administration, pups were briefly isolated from the dam and littermates and evaluated for social behavior (ultrasonic vocalization) and physiological wellbeing (temperature and activity). We found that, at 1.0 mg/kg, oxytocin significantly decreased the number of ultrasonic vocalizations compared to vehicle-injected pups. The effects of oxytocin were not socially-specific as basal body temperature and pups’ ability to thermoregulate were also significantly reduced. Additionally, oxytocin significantly reduced activity in mouse pups as measured by number of square crossings and pivots. The graded effects of oxytocin and future plans of longitudinal study are also discussed in the context of developing models of autism resulting from early environmental insult.