The purpose of this study was to examine the association between tobacco marketing efforts and daily cigarette smoking by adolescents.This was a longitudinal study of uptake of smoking on a daily basis with smoking data from the Monitoring the Future project. Diffusion modeling was used to generate expected rates of daily smoking initiation, which were compared with actual rates. Study data were from a national survey, administered annually from 1978 through 1995. Between 4,416 and 6,099 high school seniors participated per year, for a total of 94,652. The main outcome measure was a deviation score based on expected rates from diffusion modeling vs actual rates of initiation of daily use of cigarettes by ninth graders. Annual data on cigarette marketing expenditures were reported by the Federal Trade Commission.The deviation scores of expected vs actual rates of smoking initiation for ninth graders were correlated with annual changes in marketing expenditures. The correlation between sales promotion expenditures and the deviation score in daily smoking initiation was large (r = 0. 769) and statistically significant (P = 0.009) in the 1983-1992 period. Correlations between sales promotion and smoking initiation were not statistically significant in 1978-1982. Correlations between advertising expenditures and smoking initiation were not significant in either period.In years of high promotional expenditures, the rate of daily smoking initiation among ninth graders was higher than expected from diffusion model predictions. Large promotional pushes by cigarette marketers in the 1980s and 1990s appear to be linked with increased levels of daily smoking initiation among ninth graders.