The Guide to Community Preventive Service (Community Guide) methods for systematic reviews were used to evaluate the evidence of effectiveness of worksite-based incentives and competitions to reduce tobacco use among workers. These interventions offer a reward to individuals or to teams of individuals on the basis of participation or success in a specified smoking behavior change (such as abstaining from tobacco use for a period of time). The review team identified a total of 26 published studies, 14 of which met study design and quality of execution criteria for inclusion in the final assessment. Only one study, which did not qualify for review, evaluated the use of incentives when implemented alone. All of the 14 qualifying studies evaluated incentives and competitions when implemented in combination with a variety of additional interventions, such as client education, smoking cessation groups, and telephone cessation support. Of the qualifying studies, 13 evaluated differences in tobacco-use cessation among intervention participants, with a median follow-up period of 12 months. The median change in self-reported tobacco-use cessation was an increase of 4.4 percentage points (a median relative percentage improvement of 67%). The present evidence is insufficient to determine the effectiveness of incentives or competitions, when implemented alone, to reduce tobacco use. However, the qualifying studies provide strong evidence, according to Community Guide rules, that worksite-based incentives and competitions in combination with additional interventions are effective in increasing the number of workers who quit using tobacco. In addition, these multicomponent interventions have the potential to generate positive economic returns over investment when the averted costs of tobacco-associated illnesses are considered. A concurrent systematic review identified four studies with economic evidence. Two of these studies provided evidence of net cost savings to employers when program costs are adjusted for averted healthcare expenses and productivity losses, based on referenced secondary estimates.