This study compared characteristics of Korean American men in two studies: a telephone survey with a random sample of Korean American men who reported daily smoking versus a smoking cessation clinical trial with a convenience sample of Korean American men who reported smoking at least 10 cigarettes a day. Guided by the Theory of Planned Behavior (TPB), both studies attempted to explain how much its theoretical variables (attitudes, perceived social norms, and self-efficacy) would explain quit intentions in Korean American men. Participants in the cessation study were less likely to have health insurance coverage (χ² [2, 271] = 138.31, p = 0.001) than those in the survey study. The cessation group was more likely to smoke in indoor offices (χ² [1, 231] = 18.09, p = 0.003) and had higher nicotine dependence than the survey group (t₂₆₉ = 3.32, p = 0.001) but these differences became insignificant when only those who smoked 10 or more cigarettes were compared. Participants in the cessation study had more positive attitudes towards quitting (t₂₆₇ = 4.99, p < 0.001), stronger perceived social norms favoring quitting (t₂₆₉ = 5.63, p < 0.001) and greater quit intentions (t₂₆₈ = 9.86, p < 0.001) at baseline than those in the survey study. Korean American men are more likely to have a quit intention and make a quit attempt when they have more positive and fewer negative attitudes towards quitting and perceive stronger social norms favoring quitting. To motivate Korean American men to quit smoking, clinicians should underscore the immediate health benefits of quitting, promote quitting with cessation aids to reduce perceived risks of quitting in anticipation of withdrawal symptoms, and encourage family members to relate firm anti-smoking messages.