The current status of adolescent tobacco use in the United States is discussed in the context of the identification of those elements considered necessary for successful school-based smoking prevention programs. Also described are the conclusions of a National Cancer Institute-convened expert advisory panel charged with the task of addressing: What are the essential elements of a school-based smoking prevention program? The panel focused on nine areas in which sufficient data and experience existed to reach a preliminary conclusion or make a recommendation. The nine areas are: program impact, focus, context, and length; ideal age at intervention; need for peer and parental involvement; teacher training; and program implementation. The panel concluded U.S. school-based smoking prevention programs have had consistently positive effects, though these effects have been modest and often limited to delaying the onset of tobacco use. Though the panel felt many programs are suitable for dissemination, several research recommendations also are described.