Smoking cessation services are an unmet need among the homeless, who smoke at rates more than 3 times the national estimate; successful interventions in this underserved population have the potential for improving individual and public health. Contingency management (CM) is a behavioral intervention with efficacy in a number of substance use disorder populations, including smokers. However, no known studies have evaluated the effect of CM in homeless smokers. The investigators plan to examine smoking-related outcomes in homeless treatment-seeking smokers (N = 70) randomized to standard care smoking cessation (transdermal nicotine replacement therapy [NRT] + standard counseling + carbon monoxide [CO] monitoring) or standard care plus CM (NRT + standard counseling + CO monitoring + CM) conditions. Standard counseling and CO monitoring will occur for the first 4 weeks, with NRT use continuing through week 8. Participants in both conditions will meet with study staff up to twice daily on weekdays for biochemical verification of smoking status. Participants in the CM condition will have the opportunity to earn prizes for negative breath samples (CO ≤ 4 ppm) up to twice daily on weekdays. CO breath samples will be collected at all visits. The investigators expect that participants randomized to CM will have better outcomes compared to those in standard care.

Inclusion Criteria:

• age ≥ 18 years
• homeless
• regular smoker

Exclusion Criteria:

• non-English speaking
• contra-indications for transdermal nicotine
• in recovery for pathological gambling