Researchers have indicated that adult psychopathy often originates in childhood or adolescence. It has also been established that psychopathic traits are linked to disruptive behavior, criminality, and violence. As knowledge about psychopathy and its manifestations in juvenile sex offender populations remains limited, several instruments have been developed in an effort to measure the construct. In this study, we assessed how the relationship of diverse scales of psychopathy related to characteristics of sexual aggression, and determined which scales were most correlated to sexual and nonsexual delinquency. We utilized four measures of juvenile psychopathy: the Modified Childhood Psychopathy Scale (mCPS; Lynam, 1997), the Antisocial Process Screening Device (APSD; Frick & Hare, 2001; Frick, O’Brien, Wootton, & McBurnett, 1994), the Millon Adolescent Clinical Inventory (MACI; Millon & Davis, 1993; using two derived psychopathy scales), and the Inventory of Callous and Unemotional (ICU) Traits (Frick, 2003), in a sample of 191 incarcerated adolescent sex offenders located in juvenile detention facilities across a Midwestern state. We found that of the four instruments and seven subscales, only the APSD Narcissism and Impulsivity Scale was significantly correlated to a characteristic of sexual crime (i.e., number of victims, level of crime severity). No subscales were found to predict sexual crime at a significant level. However, several scales were correlated to the total delinquency score as measured by the Self-Reported Delinquency Measure. In a series of multiple regressions, the MACI Factor 2 and ICU total score were determined as the best fit to total nonsexual delinquency. Implications are offered.