Unfortunately, very little research has examined the link between antisocial personality traits in childhood and adult psychopathy. This study used data from a clinic-referred sample of 177 boys, assessed annually from recruitment (ages 7 to 12) through age 19. Parent and teacher ratings of interpersonal callousness (IC) were tested at predictors of psychopathy ratings at 18 and 19. In regression models, conduct disorder (CD) and teacher-rated IC both predicted both Factor 1 (interpersonal and affective items) and Factor 2 (impulsivity and antisocial behavior items) of the Psychopathy Checklist--Revised, as did child IQ. Prenatal tobacco exposure and cortisol measured in adolescence predicted only Factor 1. When each factor was included in the prediction of the other, CD and IC no longer predicted Factor 1 but remained significant predictors of Factor 2.