This article summarizes an impact evaluation of the North Karelia Project (Finnish CINDI program) on smoking cessation attempts. During the period 1989-1996, data were collected by annual surveys, with response rates varying from 66% to 76%. This study included 1,694 adult current smokers or persons who had quit smoking during the past year, out of a total of 6,011 respondents. Smoking cessation attempts during the past 12 months were examined as a dependent variable. Reported exposures to mass media and interpersonal health communication were examined as possible determinants of smoking cessation. Weekly exposure to mass media health messages was significantly associated with cessation attempts among men only. In contrast, interpersonal health communication, or social influence, was a significant determinant of cessation attempts among both sexes. Exposure to both mass media and interpersonal health communication had an even stronger impact on cessation attempts. Thus, interpersonal communication appears to be an important catalyst of community programs, and its inclusion should be emphasized to obtain a higher impact with community programs.