Abstract This study evaluated factors associated with adult smokers' immediate readiness to quit. Eligible smokers were proactively recruited online and invited to participate in either a telephone-based study for those who intend to quit in the next 30days (Quit Now) or a telephone-based study for those who intend to quit, but not in the next month (Quit Later). Thirty-five percent of smokers declined participation altogether. Of those who remained, 25% chose Quit Now participation. Baseline data were collected via mail questionnaire and telephone interview. Quit Now and Quit Later participants (N=1132) differed on demographic, smoking history, and psychological variables. Independent predictors of Quit Now group membership included younger age, stronger intention to quit in the next six months, greater self-efficacy to cope with temptation to smoke, and more support from significant others related to quit attempts—much of which is modifiable. Understanding factors that predict smokers' immediate readiness to quit (measured here as Quit Now group membership) could contribute to the development of smoking cessation treatments tailored for smokers who are seemingly not yet ready to quit.