The study first considers the prediction of "ever-prevalence" of delinquent and ADM behaviors from "ever-prevalence" of other delinquent and ADM behaviors. "Ever-prevalence" refers to the percentage or proportion of individuals who have committed an offense, etc., or on the individual level, to whether an individual has committed an offense, etc., in any one or more of the years under study. This is followed by an examination of substance use immediately prior to Index Offenses. The study then addresses the prediction of classification as serious delinquent, polydrug user, and mental health problem types as well as transitions between serious delinquent and polydrug user types. To examine whether the joint influence of delinquency, drug use, and emotional problems on future delinquency and drug use was additive or interactive, the study used the annual delinquency, drug use, and mental health problem types for 1976. The cross-classification of these three typologies, together with measures of future delinquency or drug use were used in a hierarchical loglinear analysis. As expected, delinquency and drug use were positively correlated. Except for the correlation between two types of drug use (marijuana and polydrug use), however, the correlations were not strong and reflected only 1 percent to 12 percent shared variance. Examination of conditional probabilities, however, indicated that despite low correlations, some strong (90 percent or more accuracy) predictive statements can be made about one type of behavior based on knowledge of another. 6 tables.