OBJECTIVES: We used nationally representative data to examine whether individuals' sexual and drug behavior patterns account for racial disparities in sexually transmitted disease (STD) and HIV prevalence. METHODS: Data were derived from wave III of the National Longitudinal Study of Adolescent Health. Participants were aged 18 to 26 years old; analyses were limited to non-Hispanic Blacks and Whites. Theory and cluster analyses yielded 16 unique behavior patterns. Bivariate analyses compared STD and HIV prevalences for each behavior pattern, by race. Logistic regression analyses examined within-pattern race effects before and after control for covariates. RESULTS: Unadjusted odds of STD and HIV infection were significantly higher among Blacks than among Whites for 11 of the risk behavior patterns assessed. Across behavior patterns, covariates had little effect on reducing race odds ratios. CONCLUSIONS: White young adults in the United States are at elevated STD and HIV risk when they engage in high-risk behaviors. Black young adults, however, are at high risk even when their behaviors are normative. Factors other than individual risk behaviors and covariates appear to account for racial disparities, indicating the need for population-level interventions.