This study examines whether nonsmokers can be mobilized to help smokers quit. We will test, via mail campaign, whether targeting nonsmokers can be equally effective in increasing smokers' quit rate as targeting smokers directly. The hypothesis is that both targeted interventions will lead to a higher quit rate than a control group, which receives one set of self-help materials. Each of the targeted intervention groups receives 10 mailings. Smoking status of all three groups will be measured at 3 and 7 months post randomization.