Despite a gradual decrease in smoking rates among adults, the proportion of youth who smoke regularly has remained stable. Among high school students in 1997, 19.9% of white, 7.2% of African American, and 10.9% of Latino youth reported smoking during at least 20 of the previous 30 days. Ethnic differences in beliefs, attitudes, and behavior about smoking have not been systematically considered in developing prevention interventions for adolescents. Effective school-based smoking-prevention interventions have been developed, but these are usually not appropriately implemented. Policy proposals and current laws that affect the marketing of tobacco to youth need to be emphasized as evidence increases that marketing by the tobacco industry targets youth and leads to more smoking. Smoking-prevention programs have been designed to involve physicians and other health care professionals in the clinical setting, but limited data exist on their efficacy. We review the guidelines for involving the clinicians who provide care to children in preventing the onset of tobacco use, counseling parents of children who smoke, and counseling adolescents who have started smoking. Finally, we summarize the future directions of smoking-prevention research and programs.