As anticipated, substance use and delinquency are positively associated, but there is little evidence that substance use leads to delinquency. Two possible exceptions to this generalization involve the role of alcohol use in sexual assault and the role of serious drug use in prolonging involvement in serious delinquency. There is evidence that minor delinquency is a necessary cause or precursor of illicit drug use, that less serious levels of delinquency are necessary causes or precursors of more serious levels of delinquency, and that less serious levels of substance use are necessary causes or precursors of more serious levels of substance use. Relationships between substance use and more serious (index) delinquency appear to be developmental, not causal. 6 tables, 62 references. (Publisher abstract)