OBJECTIVES: We explored the notion that social disadvantage increases vulnerability to the health effects of environmental hazards. Specifically, we examined (1) whether race modifies the association between blood lead and blood pressure and (2) whether socioeconomic status (SES) plays a role in this modifying effect. METHODS: Using the National Health and Nutrition Examination Survey (2001-2008) and linear regression, we estimated the association between blood lead and blood pressure. Using interactions among race, SES, and lead, we estimated this association by levels of social disadvantage. RESULTS: Black men and women showed a 2.8 (P < .001) and 4.0 (P < .001) millimeters mercury increase in SBP, respectively, for each doubling of blood lead. White adults showed no association. This lead-SBP association exhibited by Blacks was primarily isolated to Blacks of low SES. For example, poor but not nonpoor Black men showed a 4.8 millimeters mercury (P < .001) increase in SBP for each doubling of blood lead. CONCLUSIONS: Our results suggest that social disadvantage exacerbates the deleterious health effects of lead. Our work provides evidence that social and environmental factors must be addressed together to eliminate health disparities.