This study compared the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM–IV–TR; American Psychiatric Association, 2000) diagnostic 3-factor structure of posttraumatic stress disorder (PTSD) symptoms with leading 4-factor models and the newly proposed 5-factor dysphoric arousal model in a sample of 1,363 juvenile-justice-involved adolescents (990 boys, 373 girls). Structural equation modeling suggested that the 5-factor dysphoric arousal model fit significantly better than each of the other models. The model fit better for girls than for boys, and girls evidenced stronger factor loadings for items on all but the Anxious Arousal factor. The factors of the 5-factor model were then tested as mediators of the association between interpersonal and noninterpersonal trauma and mental health problems. Interpersonal trauma was associated with PTSD symptoms for boys and girls, whereas noninterpersonal trauma exposure was only associated with PTSD symptoms for boys, despite equal levels of exposure across genders, suggesting that girls may be more sensitive to the effects of interpersonal, but not noninterpersonal, trauma. Patterns in mediation were moderated by gender, as girls’ data showed stronger paths leading to depression/anxiety, somatic complaints, and suicidal ideation through PTSD symptoms, whereas for boys, paths were stronger leading to anger/irritability symptoms. Mediation results suggested differential patterns of influence for dysphoric versus anxious arousal and also indicate the importance of numbing for delinquent youth. These results add to the evidence base supporting the 5-factor dysphoric arousal model in establishing developmentally sensitive criteria for the diagnosis of PTSD among traumatized youth.