Participants in this study will be randomly assigned to receive interpersonal and social rhythm therapy for adolescents (IPSRT-A) or treatment as usual (TAU). Participants assigned to IPSRT-A will take part in 18 sessions of IPSRT over a 20-week period. Beginning with the first session, participants will meet with a therapist weekly for 16 weeks and then every other week for 4 weeks. Each IPSRT session will last about 45 to 60 minutes, and parents will be asked to accompany the child to 2 to 4 of these sessions. During IPSRT sessions, the therapist will talk with participants about their relationships and how they relate to symptoms; work with participants to help improve understanding of how their social and sleep routines relate to symptoms; and teach participants about bipolar disorder. Participants assigned to TAU will be given educational information about bipolar disorder and its treatment. They will then be referred to a mental health provider for usual care treatment.