Administered in 1987, information for this study was collected from a self-report study based on a sample of seventh and eleventh grade students from four junior and senior high schools in a mixed urban county. Results indicate that age and family have significant interactive influences on alcohol and hard drug use; age and church participation have significant interactive effects on marijuana and hard drug use as well, and age and peer interactively influence alcohol usage. The interaction of age with other factors varies by type of usage. The patterns of interaction were different between alcohol, marijuana, and hard drugs, although there were also commonalities. Various theories predicting adolescent involvement in alcohol, marijuana, and drug use may find other important sets of interactions such as gender, personality, or family background. Prevention programs should focus on three dimensions: age, factors interactive with age, and the type of substance. 5 tables, 1 figure, and 21 references (Author abstract modified)