Brief supportive telephone counseling is a promising adjunct to self-help smoking cessation programs. This article reports rates of participation, predictors of participation, and content of telephone counseling calls with nonvolunteer smokers who were identified through health surveys administered to a random sample of enrollees in a health maintenance organization. Eighty-six percent of smokers accepted at least one of three counselor calls; 66% accepted all three calls. Baseline characteristics associated with acceptance of calls included being female and greater average length of time to the first cigarette of the day. Acceptance did not differ significantly by stage of cessation. First calls with smokers who accepted all three calls were longer and were more likely to be with smokers who were willing to take a specific next action step. Overall, 12% of the sample reported having quit smoking by the third counseling call, with the highest quit rate (23%) among smokers who, at baseline, were planning to quit in the next month. Implications for large-scale interventions with smokers in health care and other organizations are discussed.