Total social isolation of macaque monkeys for at least the first 6 months of life consistently produces severe deficits in virtually every aspect of social behavior. Experiments designed to rehabilitate monkeys reared in isolation are described. While young isolates exposed to equal-age normal peers achieved only limited recovery of simple social responses, some mothers reared in isolation eventually exhibited acceptable maternal behavior when forced to accept infant contact over a period of months, but showed no further recovery; isolate infants exposed to surrogates were able to develop crude interactive patterns among themselves. In contrast to the above results, 6-month-old social isolates exposed to 3-month-old normal monkeys achieved essentially complete social recovery for all situations tested. It is postulated that social stimulation that both permits subjects to achieve contact acceptability and provides an interactive medium conducive to gradual development of sophisticated social behaviors will result in almost complete recovery of social capabilities previously obliterated by rearing in isolation.