The study compared smoking prevention in junior high schools and in high schools either receiving or not receiving a school-wide community intervention. The junior high school curriculum was delivered to all volunteers in grades 6, 7, and 8 in each intervention school. All participants were tested five times: midway through grade 6 before the intervention began, and at the end of grades 7,8,9, and 10. The primary endpoint was self-reported smoking status at the ends of grades 8 and 10. The validity of smoking reports was enhanced with collection of breath carbon monoxide samples for all subjects at all test points.