The issues of explaining and predicting smoking among adolescents is related to that of drug use of all kinds, and general models of substance use should apply to smoking as well as to consumption of other substances. The prevention program was designed to be implemented in the seventh grade during the second year of the project, with findings on smoking behavior in the first year serving as the baseline. The project of the theory of adolescent smoking was a longitudinal study of secondary school students in a community in Iowa with a population of about 23,000. The measure of differential peer association in the Iowa smoking study repeated the measure used in the Boys Town Study. The measures of differential reinforcement involved asking about both positive and negative consequences. Some of these are social, while others have to do with the physical effects of smoking, both immediate and over the longer term.