This study investigates the relationship between the self-report Youth Psychopathic Traits Inventory (YPI) and the clinician-rated Psychopathy Checklist: Youth Version (PCL:YV). A representative sample of 92 girls and 70 boys, 12 to 20 years of age (mean age, 17 years), who received services at a clinic for adolescents with substance misuse problems, was studied. Moderate correlations (r =0.30-0.51) were found between conceptually corresponding YPI and PCL:YV factor scores among both boys and girls, whereas correlations between individual subscales of the YPI and items of the PCL:YV were not as consistent. A cross-tabulation of groupings based on the three-factor models of the two instruments largely supported the categorical convergent validity of the YPI, particularly for low and high scorers. Although more studies with larger samples are needed, results indicate that the YPI is a cost-effective measure of psychopathic traits in adolescents in research settings. (Contains 5 tables.)