The evaluation of efforts to prevent tobacco use among adolescents requires accurate surveillance of both smoking prevalence and smoking initiation rates. Although several surveillance systems provide timely data about adolescent smoking prevalence (1), data characterizing rates of smoking initiation among adolescents have been limited. To improve characterization of trends in smoking initiation among young persons, data from the Tobacco Use Supplement of the 1992 and 1993 Current Population Surveys (CPS) (2) were used to estimate smoking initiation rates for persons who were adolescents (aged 14-17 years) or young adults (aged 18-21 years) during 1980-1989. This report summarizes the results of that analysis.