This study documented an association between childhood blood-lead levels and adult psychopathy. Childhood blood-lead levels, measured between the ages of 6 and 6.5 years, modestly predicted variation in the scores on the Psychopathic Personality Inventory (PPI) determined 13 to 18 years later. The results remained significant despite controls for sex, race, maternal IQ, a global measure of home environment, and academic achievement. Childhood lead levels was a significant predictor of psychopathy for four of the six PPI subscales: Machiavellian Egocentrism, Social Potency, Impulsive Nonconformity, and Blame Externalization. These four dimensions portray an individual who is callous and unemotional, highly egocentric, deflects blame for his/her behavior onto others, and consciously manipulates others for his/her own gain. The linkage between level of lead exposure and social class highlights the interconnections between environmental sources of variance in psychopathy and biological agents that can adversely affect healthy brain development. The study findings also suggest that the psychopathic features associated with high blood-lead levels may be partially due to damage to the central nervous system. The CLS recruited pregnant women in the first trimester of pregnancy from clinics located in areas high in environmental concentrations of lead. Infants were excluded if they were born premature or if their mother had any known psychiatric, neurological, or drug addiction problems. The study involved 305 infants, whose blood-lead levels were regularly assessed up to ages 19-24. Complete data were available for 250 individuals. Adult participants completed the Psychopathic Personality Inventory. 2 tables, 56 references, and appended PPI relevant subscales