This article examines the predictive value of measures of health locus of control and self-efficacy as predictors of outcomes of a widely disseminated, group-facilitated smoking cessation program. Outcomes studied were cessation for at least 1 day by the end of the program, end of program smoking status (abstinence), and smoking status at 6 months follow-up. Subjects were 257 participants in the smoking cessation program, of whom 207 made attempts to quit and 126 who were not smoking at the end of the treatment. Both pretreatment self-efficacy and health locus of control variables emerged as significant predictors of making an attempt and end of treatment abstinence. Only posttreatment self-efficacy predicted maintenance at 6 months. The results indicate the high self-efficacy is inversely related to making attempts to quit, but positively related to the success of attempts. The role of Health Locus of Control is complex and needs further investigation.