Most research on the determinants of adolescent drug use has focused on predictors of either initiation or current use. Little attention has been given to the determinants of continued use of drugs after initiation, even though some researchers have found that the consequences of continued use are more serious than those associated with experimental or occasional use. In this study, a longitudinal sample of 456 secondary and high school students who had already tried marijuana was used to examine the determinants of continued use of marijuana. Nearly 38 percent of those who had tried marijuana continued using, according to the definition operationalized in this study. Potential predictor measures were grouped in a drug-specific domain and a social context domain, and their effects on continued use, controlling for background characteristics, were examined in logistic regression models. Results showed that only the drug-specific domain had a statistically significant effect on the likelihood of continued use. Students who felt that the adverse physical and psychological effects of marijuana were not very important reasons for discontinuing use and those who had gotten stoned during their experimental stage of use were the most likely to continue use after initiation. The results suggest that the perceived physical and psychological effects of the drug are more important determinants of continued use than are social factors or benefits related to use. Any relationships between social factors and continued use are mediated by the perceived effects and risks of the drug.