Data from a statewide survey, conducted by the Indiana Prevention Resource Center, of 20,629 Indiana students in grades 5-12 were analyzed to determine the extent to which cigarette smoking predicted use of alcohol and other drugs and acted as a so-called "gateway drug." A three-stage purposive/quota cluster sampling strategy yielded a representative sample of Indiana students, stratified by grade. Cross-tabulated data revealed a strong, dose-dependent relationship between smoking behavior and binge drinking, as well as use of alcohol and illicit drugs. Daily pack-a-day smokers were three times more likely to drink alcohol, seven times more likely to use smokeless tobacco, and 10-30 times more likely to use illicit drugs than nonsmokers. A stepwise multiple regression analyzed the role that the student's perceptions of the risk of using drugs and of peer approval/disapproval of the student's drug use, gender, grade in school, and ethnic background played in predicting alcohol and other drug use.