This study examines the relationship between self-efficacy and sustained smoking cessation in Dutch quitters attending a group program for smoking cessation in 1991. Increase in self-efficacy during treatment was found to be a predictor of outcome after controlling for demographic characteristics and cessation history variables. Relapsers (n = 75) showed more negative relationships between self-efficacy and withdrawal symptoms than long-term abstainers (n = 58). Relapsers who were more depressed during the attempt under study were less self-efficacious at the end of treatment. In addition, the duration of the previous attempt to quit smoking proved to be differently associated with self-efficacy for quitters and relapsers.