A randomized clinical trial assessed the effectiveness of control, low-intensity, and high-intensity stop-smoking treatments in a Department of Veterans Affairs outpatient setting. The study actively recruited male cigarette smokers attending outpatient clinics at a university-affiliated Veterans Affairs medical center. Subjects in the control group received an informational leaflet on smoking. Subjects in the low-intensity treatment group received a self-help booklet and a 20- to 30-minute session with a trained counselor. Subjects in the high-intensity group received the low-level treatments and individually tailored follow-up treatments provided in person, over the telephone, and through the mail. At least 6 months after randomization or last treatment, biochemically verified 1-month quit-smoking rates were 1.2% in 173 control subjects, 6.3% in 143 low-intensity treated subjects, and 6.0% in 150 high-intensity treated subjects. When rigorously defined, quit rates in each of the treated groups differed significantly from the control rate, but not from each other. The results demonstrated the effectiveness of moderately intensive stop-smoking treatments in a clinical setting of considerable interest, but not the incremental effectiveness of progressively more intensive treatments.