Bipolar disorder is a brain disorder that causes dramatic changes in a person's mood and energy. Bipolar spectrum disorders, including bipolar I, II, and not-otherwise-specified (NOS) disorders, usually form in late adolescence or early adulthood and require treatment for the rest of a person's life. People with a bipolar spectrum disorder undergo periods of extreme happiness and extreme sadness, known as episodes of mania and depression. Psychotherapy has proven an effective adjunct treatment to medications for people with bipolar disorder. Interpersonal and social rhythm therapy (IPSRT) is a specific type of psychotherapy that focuses on improving problems in interpersonal relationships that are related to a person's symptoms. Researchers believe that IPSRT helps people have more regular patterns of sleep, eating, and other activities that act to set a person's biological clock. This study will specifically adapt IPSRT to the developmental needs of adolescents and will determine the effectiveness of this approach in treating adolescents with a bipolar spectrum disorder.