The boys were compared according to age at onset of maltreatment, enzyme activity, and conscience functioning in the domain of moral valuation. They were also compared in conscience functioning up to 19 years of age and with sex-matched normal counterparts. Boys who endured maltreatment prior to 36 months of age had developmental delays and interferences with functioning in more conscience domains than boys who were either spared such experiences or who endured maltreatment later in life. Subjects with low enzyme activity had significantly more interferences with authority and peer valuation than subjects with high enzyme activity. Greater interference with valuation was associated with lower enzyme activity and more frequent abuse prior to 36 months of age. Implications of the findings for future research on the psychobiology of maltreatment are discussed. 22 references and 4 tables