Ten male and 11 female Chimpanzees from 3-9 yr of age were studied to establish possible correlations between behavioral changes and hormonal changes peculiar to adrenarche and the pre-puberty period. Most of the 13 behaviors studied varied with age, body weight and hormones. For the males, the correlations were significant statistically for age, weight and plasma concentration of testosterone and of FSH. The correlations for the females were more often not significant statistically. In 10 of the 13 behaviors for the females the correlations with the sulfate of plasma dehydroepiandrosterone were in the same direction as those observed for the males with testosterone.