Participation in this single-blind study will last approximately 21 months. Participants will be randomly assigned to receive either IPT-AST, Enhanced IPT-AST, or Usual Care for 12 weeks. IPT-AST is a school-based group intervention program that focuses on prevention, psychoeducation, and interpersonal skill-building. Enhanced IPT-AST will entail IPT-AST plus three parent-adolescent sessions. Usual Care will consist of standard treatments and will not include IPT-AST. Study visits will occur before and during the intervention at baseline and Weeks 6 and 12. Follow-up visits will occur 6, 12, and 18 months post-intervention. Study visit assessments will include depression symptoms, anxiety symptoms, psychiatric diagnoses, overall functioning, social adjustment, parent-child conflict, perceived support from parents and peers, and service utilization.