Twelve rhesus infants, reared in two groups in a forest habitat. Were observed for more than one year to study their reactions to conspecifics and the effect on home range size. The infants exhibited behaviours characteristic of wild rhesus monkeys in the absence of any prior physical exposure to their conspecifics. Both peer groups established intra- and intergroup dominance hierarchies. They remained aloof from wild rhesus monkeys and showed xenophobia to stranger infants. Their home ranges increased with age and rearing experience. No change was observed in home ranges after adding more individuals.