The extent to which both traumatic life experiences and resiliency factors contributed to gang-involved delinquent behavior in adolescent males was investigated. Results indicated that the juvenile delinquent residential treatment setting participants had significantly higher levels of both Posttraumatic Stress Disorder (PTSD) symptomatology and emotional numbing than regular education high school students. Results also revealed that emotional numbing in the residential treatment setting participants positively correlated with gang-involved delinquent behavior. In addition, the low resiliency scores of residential treatment setting participants positively correlated with both gang involvement and delinquency. Practical implications of this study were discussed, including the effectiveness of screening for PTSD symptomatology when considering admission to a residential treatment facility and creating treatment goals.