The current study examined the reliability and validity of the Youth Psychopathic Traits Inventory–Short Version (YPI-S) in two different samples of at-risk adolescents enrolled in a residential program (n = 160) and at a detention facility (n = 60) in the United States. YPI-S scores displayed adequate internal consistency and were moderately associated with concurrent scales on other self-report psychopathy measures and externalizing behaviors. YPI-S scores were moderately related to interviewer-ratings of the construct using the four-factor model of the Psychopathy Checklist: Youth Version. Findings suggest that the YPI-S may be a clinically useful and valid tool for the assessment of psychopathic traits in juvenile settings. This may be particularly true given the differential predictive utility of each of its dimensions.