Cigarette smoking is a vitally important public health problem. Tobacco use is the leading preventable cause of death and disability in the United States and the prevalence of cigarette smoking among adults is currently about 25%, representing almost 50 million Americans. Public health efforts to date have been successful in making smokers aware of the health risks of tobacco use and most smokers express a desire to quit. Yet only a small percentage are able to do so in any given year. Although research has been successful in developing efficacious smoking interventions, their dissemination and, thus, public health impact have been limited by the fact that smokers frequently choose not to participate in them. How to induce more smokers to participate in these programs is an important question that to date has been given little research attention. The proposed research is designed to experimentally address this critical issue in the context of a worksite-based intervention. Twenty-four worksites will be randomly assigned to one of six experimental conditions defined by the use or not of direct incentives for participation and cessation, crossed with the use of either an intensive group program, a self-help program, or a choice of either group or self-help programs. Three six-month rounds of smoking cessation programs will be offered at each site. A cohort identified at baseline of all smokers at these sites will be followed for 24 months to explore the effects of incentives and program type on both participation in programs and smoking cessation rates; the demographic, job-related, and psychosocial characteristics associated with participation in different types of programs; and the relative cost-effectiveness of each of the six incentive-program type combinations.