The epidemiologic transition theory presented first by Omran [Omram. A. R. (1971) The epidemiologic transition: a theory of the epidemiology of population change, Mildbank Quarterly 49(4), 509-538] was designed to explain global trends in the dynamic relationship between epidemiological phenomena and demographic change. This paper argues that universalizing this theory only partially serves to explain mortality declines over the last century and eclipses key epidemiologic differences between population subgroups based on socioeconomic status, race, and sex. This paper examines morbidity and mortality differentials between population subgroups and demonstrates important inconsistencies with the optimistic trends implied by the epidemiologic transition theory, an argument further developed using the HIV/AIDS pandemic as a case study. The paper argues that these differences should be brought from margins to center to present a more complex and comprehensive picture of how population subgroups experience epidemiologic transitions differently.