This is the first study that tested the psychometric properties of the Child Problematic Traits Inventory (CPTI) in clinic-referred children (ages 6-13 years). Teachers (N = 159) and parents (N = 173) completed the CPTI and various other measures. Confirmatory factor analyses supported the CPTI's three-factor structure when teachers and parents rated the 28 CPTI items. Teacher- and parent-reported CPTI scores showed the expected relations with external correlates (e.g., conduct problems and proactive aggression). Crucially, the validity of the CPTI scores was also supported across informants (i.e., when linking teacher-reported CPTI scores to parent-reported external correlates, and vice versa) and across methods (i.e., regardless if a questionnaire or a diagnostic interview was used to measure external correlates). We conclude that the CPTI holds promise as a research tool for assessing psychopathic traits in clinic-referred children. Until our findings have been replicated and extended, the CPTI should not be used for clinical decision making.