The SSDP is a longitudinal study involving all 5th grade students who were attending 18 Seattle elementary schools in September 1985. Nested structural equation modeling was applied to data from the SSDP, with stability effects and cross-sectional correlations controlled, to examine the cross-lagged effects of alcohol use on interpersonal aggression, as well as the effects of interpersonal aggression on alcohol use. Data indicated a reciprocal effect of interpersonal aggression and alcohol use in later adolescence. Sex of the subject did not significantly moderate the observed relationships. When shared risk factors for alcohol use and interpersonal aggression were controlled, the relationships were not seriously attenuated. Although the results suggest that reducing one behavior will probably not have a long-term impact on the other, early prevention efforts aimed at shared risk factors may reduce both contemporaneously. 55 references, 3 tables, and 5 figures