This study examined the relation of conduct problems and depressed mood to tobacco, alcohol, marijuana, and other drug use in 6th through 11th grades. A total of 200 at-risk 6th-grade boys completed an extensive assessment that involved interviews, home observations, questionnaires, test data, telephone interviews, court records, and school questionnaires and records. The boys' levels of depression and substance use were self-reported. Based on the assessments, subjects were categorized into four groups: (1) conduct problems only; (2) depressed mood only; (3) both depression and conduct problems; and (4) neither problem. Levels of substance abuse were plotted each year. Results showed that boys with conduct problems in sixth grade showed elevated substance use at adolescence, particularly for tobacco, marijuana, and other drugs. Boys who were only depressed did not show increased risk for substance use through adolescence. Conduct problems in 6th grade were predictive of substance use through 11th grade. Of the various forms of substance use, alcohol use was least associated with conduct problems. One table and eight figures are attached. (MM)