Background. This study quantifies resources used to conduct 26 community-wide quit-smoking contests, the percentage of smokers that participated in these contests, and the statistical associations between resource inputs and participation percentages. Methods. Data collected from the 11 COMMIT intervention communities (adult population range 47,490-185,913) included number of contest participants, contest procedures, and resource inputs. Stepwise regression was used to find the most meaningful association(s) of independent variables with contest participation percentage. Results. Contest participation percentages ranged from 0.27 to 3.11% of smokers (mean = 1.26%). Total cost (COMMIT and community-contributed resources and dollar expenditures) to conduct a contest averaged $24,857 (range $5,751-$74,556), or $78.57 per contest participant. Expenditures in various specific resource categories varied greatly. Total expenditures per smoker in the community (excluding expenditures for prizes) was the independent variable most highly correlated with contest participation percentage, accounting for 63% of the total variability in participation percentages. Conclusions. The percentage of smoker participation in community-wide stop-smoking contests appears primarily to be a function of total resource expenditures, regardless of the specific types of resources funded. Stop-smoking contests are judged to be quite cost effective. Study strengths and weaknesses are discussed. (C) 1995 Academic Press, Inc.