Data were collected as part of the Rutgers Health and Human Development Project, a prospective longitudinal study of adolescent developments. Subjects were initially tested between 1979 and 1981 at the ages of 12, 15, and 18 years. Of 1,380 subjects included in the first wave, 1,201 were tested in the three subsequent waves. Data were obtained from self-report questionnaires that included several measures of alcohol, marijuana, and cocaine use. Drug users were asked to indicate how often they engaged in fighting or hurting someone while they were using drugs or because of drug use. Results showed the prevalence of fighting while using drugs was higher for alcohol than for marijuana and cocaine. A series of nested structural equation models examined cross-sectional and long-term relationships between each type of drug use and aggressive behavior. While alcohol use was not significantly related to later aggressive behavior at any age, the use of both marijuana and cocaine was significantly related to later aggression. In contrast, aggressive behavior did not significantly predict later alcohol, marijuana, or cocaine use. Overall, findings suggest long-term and acute relationships between aggression and drug use vary by drug type and life cycle stage. 50 references, 1 note, 1 table, and 6 figures