Tobacco use is the single leading preventable cause of death in the United States, and the risk for smoking-attributable disease increases the earlier in life smoking begins. Trends in the initiation of cigarette smoking are important indicators for directing and evaluating prevention activities. CDC and the Substance Abuse and Mental Health Services Administration (SAMHSA) analyzed self-reported data from the National Household Survey on Drug Abuse (NHSDA) for 1994-1997 to study the incidence of initiation of first cigarette smoking and of first daily smoking in the United States during 1965-1996 among persons aged < or =66 years and to estimate the number of new smokers aged <18 years. The findings from the analysis indicated that, during 1988-1996 among persons aged 12-17 years, the incidence of initiation of first use increased by 30% and of first daily use increased by 50%, and 1,226,000 persons aged <18 years became daily smokers in 1996.