This study examines drug selling among representative samples of high school students in Ontario. It involves three approaches, (i) examining the trend in drug selling between 1983 and 1989, (ii) assessing differences between sellers and non-sellers on demographic characteristics, levels of alcohol and drug use, and problems, and (iii) drawing detailed profiles of drug seller types. Drug selling declined considerably between 1983 and 1989. Sellers were more likely to be males and to use alcohol and drugs more often than non-sellers. Sellers also had more alcohol and drug problems and engaged in more delinquent acts. Drug sellers who sold cannabis only were less frequent users of drugs, less likely to have drug problems, and were also delinquent.