The primary aim of this study is to evaluate the effects of 12 weeks of varenicline as compared to NRT, using a two-group randomized placebo-controlled design on smoking cessation rates for 12 months among 274 outpatients in treatment for SUD. The counseling incorporates BA (adapted slightly for sobriety settings by directly addressing barriers and concerns expressed by substance abusers), skills training and medication management. Confirmed point-prevalence and sustained abstinence will be assessed at 3, 6 and 12 months after the start of treatment. Secondary aims will examine potential mediators of effect including within-treatment abstinence, craving, and nicotine withdrawal levels.