Smoking cessation treatment is highly cost effective and pharmacotherapy is universally recommended for treatment of nicotine dependence. However, the majority of smokers are unable to quit even with treatment. Existing and new pharmacotherapies along with prevention efforts are key to improving smoking cessation rates and reducing the premature morbidity and mortality associated with tobacco use. The purpose of this study is to examine the effectiveness of bupropion as an addition to a standard smoking cessation treatment of CBT and nicotine replacement. In addition, this study will determine if bupropion improves an individual's odds of quitting smoking, and whether this is achieved through its impact on negative mood states associated with depression.