Results: There was a significant net change from base- line to the end of the semester (after the intervention) between treatment and control schools for students who were regular smokers, but not for students who were non- smokers or light smokers. Regular smoking decreased 3.8% in treatment schools and increased 1.5% in con- trol schools (P .001). Regular smoking continued to de- crease at 6 months after the intervention in treatment schools, with a total change in prevalence from 25.1% to 20.3%. Involvement in community-advocacy activi- ties and the 3 social constructs—perceived incentive value, perceived self-efficacy, and outcome expectancies— also showed significant net changes between treatment and control schools (all P values .01).