 Cigarette smoking remains the number one cause of preventable premature death in the U.S., annually killing more than 400,000 Americans. Without reversal of adolescent smoking trends, five million of todays youth will die prematurely of smoking-related illnesses. The 16-year Hutchinson Smoking Prevention Project HSPP was conducted in 1984-1999 to 1 address challenges of trial design and execution in school-based smoking prevention by developing the most rigorous school-based randomized trial possible, and 2 use the trial to answer the scientific questions, To what extent can a theory-based, social-influences smoking prevention intervention spanning elementary, middle and high school grades reduce smoking among youth at 12th grade and two years post-high-school? 