Inclusion Criteria:

1. SCID for DSM-IV diagnoses of bipolar I or bipolar II disorder, and nicotine dependence.
2. Young Mania Rating Scale Total Score <12 at study entry.
3. BPRS Total Score < 20 at study entry
4. HAM-D 17-Item Score >12 and <25 at study entry. NB: We have set an upper limit for allowable HAM-D 17-item scores since higher scores would typically trigger the initiation of an antidepressant trial, and this study involves a placebo-controlled augmentation of existing medication therapies with bupropion.
5. Fagerstrom Test for Nicotine Dependence (FTND) score of 4 or more.
6. Smoking at least 15 cigarettes per day, and have expired breath CO level >10 ppm and plasma cotinine level >150 ng/ml at baseline.
7. Be on a stable dose of a mood stabilizer for at least 1 month (e.g. lithium, valproate, carbamazepine, atypical antipsychotic) as judged by the study psychiatrists (T. George, M.D. and H. Blumberg, M.D.), and judged by well-trained trained psychiatric clinicians (e.g. J. Vessicchio, M.S.W. or K. Sacco, Psy.D.) to be in remission from active manic, hypomanic, major depression and psychotic symptoms based on a clinical interview and SCID-IV.
8. Be able to provide informed consent to participate in this study as judged by clinical evaluation, and scoring at least 80% on a post-consent "test".

Exclusion Criteria:

1. Meet criteria for current abuse or dependence for any other alcohol or illicit substance within the past 3 months of study enrollment.
2. Current evidence by SCID-IV and clinical evaluation of suicidality, homocidality or psychosis.
3. Meet DSM-IV criteria for current major depression at the time of baseline evaluation.
4. A history of hypersensitivity or other known adverse reactions (e.g. hyperstimulation, severe agitation) to bupropion.
5. Any serious documented medical disorders which might be contraindicated with bupropion (i.e. anorexia or bulimia nervosa, history of seizure disorder, history of major head injury with loss of consciousness for a period greater than five minutes), or if the results of psychiatric/medical screening suggest reason concern of a trial of bupropion (e.g., a history of severe cardiac, renal or hepatic disease, diabetes mellitus or thyroid abnormalities which in the opinion of the study internist Dr. Lynn Sullivan would preclude participation in this study).
6. Evidence of clinically significant EKG abnormalities as judged by the study internist, Lynn E. Sullivan, M.D. (Department of Internal Medicine, YUSM), or her designate.
7. Prescription of monoamine oxidase inhibitors or the Wellbutrin® formulation of bupropion.
8. The presence of manic, mixed manic or hypomanic symptoms in the past one (1) month prior to study enrollment.
9. A lifetime history of antidepressant-induced mania or hypomania.
10. A history of suicidal ideation while taking antidepressants.