This study examined whether switching to low-tar cigarettes predicts future quit attempts or smoking cessation. Prior studies of whether switching to low-tar cigarettes increases or decreases cessation behavior have produced contradictory results. We believed a large, prospective population-based study was needed. Participants in the Community Intervention Trial for Smoking Cessation (COMMIT), who were smokers in 1989 and 1991 and provided their smoking status in a 1993 interview, provided product code information so that the tar categories of their cigarettes could be identified. Smokers' brands were classified as ultralight (0-6 mg tar), light (7-15 mg tar), and regular (16+ mg tar). The main predictor measure was switching to a lower tar yield category: 8% of baseline light smokers and 19% of baseline regular smokers switched to a lower yield product between 1989 and 1991. The main outcome measures were attempts to quit and successful 6-month cessation. Despite greater desire to quit among switchers, switching down was not associated with increased or decreased number of attempts to quit or the likelihood of future cessation. No evidence of differential effects was found for subgroups of smokers, including those who did and did not believe that low-tar cigarettes are safer. The data show that switching to a low-tar cigarette does not appear to increase or decrease the likelihood of future cessation, though motivation to stop smoking may be associated with switching.