The Agency for Health Care Policy and Research (AHCPR) guidelines on smoking cessation recommend that primary care physicians provide both brief advice against smoking and follow-up care for all smokers. Surveys show that although physicians understand the importance of smoking cessation, the actual implementation of these guidelines is limited. The main objective of our study was to evaluate the comparative effectiveness of 2 different approaches to smoking cessation counseling: practice-based and community-based. Both smoking cessation approaches consisted of 1 recruitment session and 6 computer-assisted counseling sessions. In the practice-based approach, counseling was provided by office nurses and telephone counselors; in the community-based approach, the counseling was given by telephone counselors only. Four practices in 3 mid-Michigan communities participated, including 120 physicians and 487 patients who were smokers. The physicians were trained to provide brief advice for smoking cessation consistent with the AHCPR guidelines; the nurses and telephone counselors were trained in relapse prevention, computer skills, and individual case management. Sixty-two percent of the participants obtained free nicotine replacement therapy. At 6 months, quit rates (7-day smoke-free status) were 35% in the practice-based group and 36% in the community-based group. Participants who completed at least 4 sessions showed higher quit rates than those who did not. Nurses in primary care practices and counselors can be trained to deliver effective relapse-prevention counseling during office visits and by telephone. Our study showed an increase in the reported rates of smoking cessation by using these counseling methods.