Six and 12-month outcomes are reported on 79 mentally ill persons attending either a 4- or 8-session community-based smoking cessation group. Quit rates at post, 3-, 6-, and 12-month follow-ups were 16, 19, 16, and 19%, respectively, with no significant effect of program length. These success rates are comparable to outcomes reported following group-based treatment with mentally healthy smokers. The majority of quitters used nicotine replacement therapy. Psychotropic medication dosages did not vary over time in quitters or non-quitters. No reductions in smoking were observed among non-quitters. Quitting smoking had no untoward effects on symptoms of mental illness or general functioning.