The long-term objective of this research is to improve smoking cessation rates by developing a manualized, partner-involved, smoking cessation intervention. Social support from romantic partners has been found to predict sustained abstinence rates. However, there is no current manualized approach that specifies how to directly involve non-smoking partners in smoking cessation treatment. Across numerous randomized trials with alcohol or drug abusing populations, those who receive Behavioral Couples Treatment (BCT) versus individual-only treatment demonstrate significantly greater long-term abstinence rates, improved pharmacotherapy compliance, and reduced risk for relapse for up to two years post-treatment. In this behavioral therapies development application, we propose to test BCT for smoking cessation (BCT-S) using guidelines specified by Rounsaville et al., (2001). The primary aims are threefold. The first aim is to conduct Stage 1a work to test and refine BCT-S with 12 initial cases of smokers and their non-smoking spouse or cohabitating partner. From these cases we will generate: a working version of the BCT-S therapist manual, other intervention materials, training procedures, and treatment adherence and competence measures. The second primary aim is to pilot in a randomized trial the efficacy of BCT-S compared to individually-delivered standard smoking cessation treatment (ST) with 60 smokers and their non-smoking romantic partners. The purpose of this work will be to demonstrate feasibility, participant acceptability, and efficacy with an effect size estimate in order to determine sample size requirements for BCT-S in a future larger-scale randomized clinical trial. Outcomes will be assessed at immediate post-treatment and again at 3-month and 6-month follow-ups. The third aim is to explore the potential process mechanisms that may underlie the efficacy of BCT-S such as increased transdermal nicotine patch compliance and greater perception of smoking-specific positive support relative to negative support behaviors. Lay description: Approximately 85% of diagnosed cases of lung cancer are attributed to smoking. For nonsmoking spouses, 35% have greater risk of cancer compared to those in non-smoking relationships. This research seeks to help smokers quit cigarette smoking with the support of their non-smoking partners.