Background: In adolescents and adults, bipolar disorder (BD) is associated with significant morbidity, mortality, and impairment in psychosocial and occupational functioning. IPSRT is an empirically supported adjunctive psychotherapy for adults with bipolar disorder, which has been shown to help delay relapse, speed recovery from a bipolar depressive episode, and increase occupational and psychosocial functioning in adults with BD. This study is designed to describe the adolescent-specific developmental adaptations made to IPSRT (i.e., IPSRT-A) and to report the results from an open trial of IPSRT-A with 12 adolescents with a bipolar spectrum disorder. Method: Interpersonal and Social Rhythm Therapy was adapted to be developmentally relevant to adolescents with bipolar disorder. Twelve adolescents (mean age 16.5±1.3 years) diagnosed with a bipolar spectrum disorder participated in 16–18 sessions of adjunctive IPSRT-A over 20 weeks. Manic, depressive, and general symptoms and global functioning were measured at baseline, monthly during treatment, and at post-treatment. Adolescent satisfaction with treatment was also measured. Results: Feasibility and acceptability of IPSRT-A were high; 11/12 participants completed treatment, 97% of sessions were attended, and adolescent-rated satisfaction scores were high. IPSRT-A participants experienced significant decreases in manic, depressive, and general psychiatric symptoms over the 20 weeks of treatment. Participants' global functioning increased significantly as well. Effect sizes ranged from medium-large to large. Conclusions: IPSRT-A appears to be a promising adjunctive treatment for adolescents with bipolar disorder. A current randomized controlled trial is underway to examine effects of adjunctive IPSRT-A on psychiatric symptoms and psychosocial functioning. Depression and Anxiety, 2010. © 2010 Wiley-Liss, Inc.