Although ADHD and CD are apparent risk factors for adult psychopathy, there are three distinct perspectives regarding their relationships to psychopathy: (1) ADHD may contribute uniquely to the development of psychopathy or (2) its contribution may reflect its high comorbidity with CD. Alternatively, (3) the comorbid presence of ADHD and CD may confer unique risk for the development of psychopathy. Although prior adult studies have yielded conflicting findings, no prior studies of adolescents address this issue. We examined these three hypotheses and the possibility of sex differences using cross-sectional analyses in 90 male and 123 female incarcerated adolescents. Among males the influence of ADHD was largely attributable to the overlap between ADHD and CD, whereas among females ADHD contributed independently to psychopathy scores and to scores on several dimensions of psychopathy. In addition, among females, the ADHD × CD interaction was significant for the total score and the antisocial component of psychopathy and in a direction opposite to that predicted by the comorbid subtype hypothesis. These findings indicate that there may be sex-specific pathways to elevations in psychopathic traits and suggest that the comorbid subtype hypothesis is probably not correct for either boys or girls. Copyright © 2009 John Wiley & Sons, Ltd.