[School-based tobacco prevention: the "Be Smart - Don't Start" program].

The competition for smoke-free classes, the "Be Smart - Don't Start" program has been implemented in Germany since 1997. Using contract management techniques, school classes participating in the competition commit themselves to abstain from smoking for six months. Classes report on a regular basis whether they have stayed smoke-free or not. After the end of the competition period, successful classes participate in a prize draw. The competition aimes to influence social norms.Over the past 20 years, the competition has become a major school-based intervention to prevent smoking in Germany. Several studies addressed process and outcome evaluation, cost-benefit efficacy and iatrogenic effects. Following the evidence so far, the intervention is feasible for implementation in school routines, evokes positive feedback in teachers and students, and reveals a positive cost-benefit ratio. Findings from controlled studies imply that negative side-effects are unlikely to occur and that participation in the competition affects the progression of smoking positively at least in the short term.