The psychometric properties of the Child PTSD Symptom Scale (CPSS) were examined in 2 samples. Sample 1 (N = 185, ages 6-17 years) consisted of children recruited from hospitals after accidental injury, assault, and road traffic trauma, and assessed 6 months posttrauma. Sample 2 (N = 68, ages 6-17 years) comprised treatment-seeking children who had experienced diverse traumas. In both samples psychometric properties were generally good to very good (internal reliability for total CPSS scores =.83 and.90, respectively). The point-biserial correlation of the CPSS with posttraumatic stress disorder (PTSD) diagnosis derived from structured clinical interview was.51, and children diagnosed with PTSD reported significantly higher symptoms than non-PTSD children. The CPSS demonstrated applicability to be used as a diagnostic measure, demonstrating sensitivity of 84% and specificity of 72%. The performance of the CPSS Symptom Severity Scale to accurately identify PTSD at varying cutoffs is reported in both samples, with a score of 16 or above suggested as a revised cutoff.