Participation in this study will last about 8 months. All participants will first undergo initial assessments that will include a combination of structured interviews, self-report measures, rating scales, and reviews of program behavioral records and incident reports. Participants will then be assigned randomly to receive JJAM for Girls plus treatment as usual or treatment as usual alone. Participants receiving JJAM for Girls will attend two 1.5-hour sessions per week for 8 weeks. Sessions will aim to help youth develop skills in the following areas: identifying different types of physical and relational aggression, recognizing early warning signs of anger, avoiding anger-provoking situations, managing anger to prevent aggression, solving problems, communicating about anger-related events, and repairing relationships damaged by anger-related behaviors. Participants will also complete between-session practice activities that will include practicing skills involved in planning personal goals. Treatment as usual for all participants will include all standard activities in the female juvenile justice program. All participants will repeat the initial assessments at treatment completion and Month 6 of follow-up.