Abstract: To address the diverse health effects of posttraumatic stress disorder (PTSD) in youth, reliable and valid screening and diagnostic instruments that can be adapted to the specific context in which they are used, are required. Here, we assessed the psychometric properties (factorial validity, concurrent validity, and internal consistency) of the Child PTSD Checklist in treatment-seeking youth using secondary data. The scale demonstrated high internal consistency (Cronbach α = 0.93). Exploratory factor analysis revealed a three-factor structure (anxiety and avoidance, anger and dissociation, and depressive symptoms) that accounted for 41.9% of the total variance. Concurrent validity was fair between the Child PTSD Checklist and the diagnostic Kiddie Schedule for Affective Disorders and Schizophrenia, Present and Lifetime version when assessing for PTSD. The Child PTSD Checklist seems to be a promising tool for assessing PTSD in trauma-exposed youth in clinic settings. However, further studies are needed to address the checklist’s broader utility.