This study assessed whether income inequality and primary care physician supply have a different effect on mortality among Blacks compared with Whites. We conducted a multivariate ecologic analysis of 1990 data from 273 US metropolitan areas. Both income inequality and primary care physician supply were significantly associated with White mortality (P < .01). After the inclusion of the socioeconomic status covariates, the effect of income inequality on Black mortality remained significant (P < .01), but the effect of primary care physician supply was no longer significant (P > .10), particularly in areas with high income inequality. Improvement in population health requires addressing socioeconomic determinants of health, including income inequality and primary care availability and access.