 The HSPP trial used a group-randomized, matched pair design with the school district as the experimental unit. Of 40 participating school districts, 20 were randomly assigned to the experimental intervention condition and 20 were assigned to the control no HSPP intervention condition. No restrictions were placed on the health promotion or tobacco use prevention activities of the control districts, thus enabling schools to continue whatever health curricula were normally offered. Main endpoints were daily smoking at 12th grade and 2 years after high school Plus-2. Study participants N8,388 were two consecutive third grade enrollments in each of the 40 school districts. All third graders were followed to endpoint, including those who dropped out of school or otherwise left their school districts. The study achieved a 94 follow-up rate at the Plus-2 endpoint. 