Despite significant declines in cigarette smoking rates among adults in the United States in the last few decades, smoking rates remain high among poor and underserved populations. One underserved group is the 4 million homeless persons in the US among whom cigarette smoking rate is an alarming 70% or more; these rates are 3 times higher than national average. Two of the three leading causes of death among homeless persons, heart disease and cancer are tobacco related.2, 3 Despite very high smoking prevalence and disease burden in this population smoking cessation research have not been extended to the homeless. Recent studies including data from our research team show a considerable degree of readiness to quit smoking by homeless smokers and that nicotine replacement therapy (NRT) plus counseling show promise. However, homeless persons face many challenges that may constitute barriers for them to adhere to smoking cessation treatments even if such treatments have been proven effective in the general population. In order to reduce smoking-related health disparities within this underserved population, it is critical that cessation interventions including strategies to improve treatment adherence be developed to include homeless smokers. The primary aim of this study is to assess the effects of adherence-focused motivational interviewing (MI) to help homeless persons quit smoking.