Extensive child health supervision, with emphasis on counseling and anticipatory guidance, was provided for the first three years of life to an experimental series of 47 normal first-born black infants from low-income families living in the environs of Children's Hospital in Washington, D.C. The mothers were unmarried schoolgirls in normal physical and mental health. A control series consisted of 48 similar mother-child dyads from the same area. Data were collected, in part by an outside evaluator, at yearly intervals on both experimental and control series in a form suitable for coding on computer cards. Comparison of differences in behavioral results between the two series showed statistically significant findings in favor of the experimental children, as well as numerous favorable trends during the first six years of life. Positive effects became evident in diet and eating, habits, in some developmental problems of growing up (such as toilet training), and in certain abstract qualities including self-confidence. Significant differences were also noted between the experimental and control mothers for various child rearing practices and personality characteristics. No significant difference or trend favored the control series. We believe that a causal relationship existed between the intervention and at least some of the significant findings.