The aim of the study is to develop and pilot test a cognitive-behavioral (CBT) intervention for young adults, ages 18-24 with bipolar disorder. The 14-week intervention focuses on improving management of bipolar disorder, reducing involvement in high-risk behaviors, and enhancing psychosocial functioning. The intervention also focuses on issues specific to transition-age youth. The study includes two phases: In phase 1, the intervention will be developed, refined, and openly piloted with several participants. In phase 2,the investigators will conduct a randomized clinical trial, in which 40 participants will be randomized either to receive the intervention right away, or to a 14-week waitlist condition. Participants will be evaluated at baseline, week 5, week 10, and week 14 of the study period, as well as at 3- and 6-month follow up, using measures of mood symptoms, high-risk behaviors, drug and alcohol use, and psychosocial functioning.