The AIMS study compares a methamphetamine-specific treatment intervention to a treatment-as-usual Functional Family Therapy (FFT) approach for adolescents ages 15 to 19. Adolescents are assigned to one of two treatment conditions: (1) 16 weeks of FFT designed to strengthen family relationships and develop skills for helping the adolescent avoid drug use; or (2) 16 weeks of a combination of FFT and a methamphetamine-specific intervention involving group and individual therapy sessions; Families are assessed using questionnaires and interviews, and adolescents participate in neuropsychological testing, before, during, and after treatment to provide information about family functioning, the adolescent's drug use, the adolescent's peers, and other factors that may contribute to treatment success. Adolescents also provide urine specimens for drug screening at assessment visits. Through a partnership with Oregon Health and Science University (OHSU), adolescents will participate in functional magnetic resonance imaging appointments at the hospital to examine regional brain blood flow during tasks designed to measure impulsivity and risk-taking behaviors. As a treatment development grant, study investigators will study adolescents' acceptance of and response to the newly developed methamphetamine-specific treatment approach.