The investigators propose to conduct a 20 week open pilot study of Interpersonal and Social Rhythm Therapy (IPSRT) to treat individuals (n=18) with subthreshold bipolar (BP) who are currently depressed. The investigators will conduct a preliminary evaluation of sleep-wake and social rhythm patterns in study participants using questionnaires and actigraphy. Primary aims of this study are to evaluate feasibility of this treatment and assessment approach. Exploratory aims are to examine 1) sleep-wake and social rhythm patterns in subthreshold BP, 2) impact of IPSRT on symptoms and functioning over time and 3) relationship between sleep-wake and social rhythm patterns and treatment outcomes.