Objectives:Using a participatory research approach, this study reports the efficacy of the Communities Engaged and Advocating for a Smoke-free Environment (CEASE)-4 intervention offered by the local peers.Methods:CEASE-4 is a theory-based tobacco-cessation intervention, tailored to the needs of underserved populations. 842 tobacco users self-selected into: a) self-help (n= 472), b) single-session class (n= 163), and c) four-session class (n= 207). While self-help group only received educational materials, curriculum for other arms was built on the social cognitive, motivational interviewing, and trans-theoretical- frameworks. Participants could also receive nicotine replacement therapy (NRT). Outcome was self-reported smoking cessation measured 12 weeks after completion of the intervention, validated by exhaled carbon monoxide (CO) test.Results:Quit rate was statistically different across groups, with highest quit rate in four-session and lowest quit rate in self-help arm. Cessation rates at follow up (12 weeks after completion of the intervention) were 2.3% in the self-help arm, 6.1% in the single-session arm and 13.0% in the four-session arm.Conclusion:While theory-based smoking cessation services are effective for underserved populations, four-session curriculum might be superior to a single session program.