This paper aims to assess program bonus effects on adult tobacco use from a long-term intervention that targeted adolescent tobacco use. The school-based community intervention started in Västerbotten County in Sweden in 1993 and adults were invited to support adolescents to stay tobacco-free. It was combined with repeated cross-sectional surveys in schools annually 1994-99 among grades 7-9 and after 1999 every second year. Participating schools were randomly selected before the first survey representing both rural and urban settings. Out of 4,055 students, 1,008 (24.8%) reported that their supporting adult had been a tobacco user who quit tobacco in order to be allowed to participate. Out of these, 13.2% used tobacco daily before joining. The remaining 2,997 students' adult partners were not tobacco users. Engaging tobacco using adults as partners in interventions targeting adolescent tobacco use seem to have a considerable tobacco-reducing bonus effect in the adults.