This guide to school-based smoking prevention programs for educators is the product of five years of work to prevent cancer. The National Cancer Institute (NCI) is currently funding 23 coordinated intervention trials directed at youth. Although not all the studies are complete, sufficient results are available to recommend the most effective smoking-prevention techniques to educators. This booklet presents the results of experts convened by the NCI to review the available data on adolescent smoking prevention and to determine which prevention strategies warrant wider use. These recommendations include simple, practical lessons that should be useful to school administrators, health educators, and teachers who develop, authorize, or implement smoking prevention and who determine which prevention strategies warrant wider use. This study does not contain detailed curricula or lesson plans; instead, it offers statistics on smoking usage and trends and outlines eight strategies and eight recommendations to prevent smoking in adolescents. Also included is an annotated list of some available resources for school-based smoking programs along with some selected references. (RJM)