The present study attempted to identify predictors of smoking cessation in a cohort of cigarette smokers followed over 13 years. Data are reported on 6,603 persons who resided in one of 20 U.S. communities involved in the National Cancer Institute's Community Intervention Trial for Smoking Cessation (COMMIT) study, were current smokers in the COMMIT trial in 1988, and completed detailed tobacco use telephone surveys in 1988, 1993, and 2001. A person was classified as a former smoker if at the time of follow-up he or she reported not smoking for at least 6 months prior to the interview. Reasons and methods for quitting also were assessed in 1993 and 2001. Among smokers in 1988, 24% had stopped smoking by 1993 and 42% were not smoking by 2001. The most frequently cited reasons for quitting were health and cost reasons, while assisted methods to quit were more common in more recent years. Measures of nicotine dependence were much more strongly associated with cessation than measures of motivation. Other predictors included male gender, older age, higher income, and less frequent alcohol consumption, although the gender effect no longer existed when cessation from cigarettes as well as other tobacco products was considered as the outcome. The present study shows that nicotine dependence is a major factor predicting long-term cessation in smokers. This finding has implications for tobacco control policy and treatment approaches.