EARLY MATERNAL deprivation and impoverished environments have been reported to produce dire consequences for the human infant. Deprived infants are said to weigh considerably less, be more susceptible to disease, and show a higher mortality rate than normally-reared infants. 1-4 In addition, a variety of behavioral anomalies have been related to inadequacies, particularly social, in the early environment. 5-7 Because of the physical and psychosocial similarities between chimpanzees and man, and the greater possibilities of experimental manipulation with nonhuman Ss 5,8 we have undertaken the systematic study of maternal deprivation in the chimpanzee. 6,9,10 In previous studies, most infants were isolated from social beings and inanimate objects beginning on day 1 post partum. Results indicated that in terms of mortality rate, physical health, and weight gain, deprivation had no adverse consequence for the chimpanzee. Indeed, even infants raised in our (maximally restricted) environments weigh more