The present study assessed the unique versus cumulative effects of physical and sexual assault, on patterns of substance-use in adolescents. It was hypothesized that experiencing a single assault (physical or sexual) when compared with exposure to both physical and sexual assault would be more strongly related to membership of polysubstance use classes. From the National Survey of Adolescents-1995 (N = 4,023) 918 adolescents (age range = 12-17 years, M = 14.92, 49.6% female) with reports of physical assault and/or sexual assault were selected. Using information on alcohol-use, cigarette-smoking, chewing tobacco, non-prescribed use of medicines, and drug-use, latent class analysis indicated a three class solution for substance-use, namely, Experimental use, Light polysubstance-use, and Polysubstance-use. Multinomial logistic regression analyses indicated that as compared to adolescents exposed to a single type of assault those exposed to both physical and sexual assault were two-to-three times more likely to be in the heavier polysubstance-use class. Females were more likely to be members of the polysubstance-use class than of the experimental use class. Gender did not emerge as a significant moderator. It was concluded that assessing for single type or co-occurring assault can facilitate identification of adolescents at elevated risk for polysubstance-use.