In this article, I argue that research on social stratification, on intergenerational transmission of inequalities, and on the theory of factor payments and wage determination will be strengthened by studying the role played by early childhood health. I show that the inclusion of such a factor requires researchers to integrate theories in each of these fields with new theories linking early childhood health conditions and events that occur at later stages in the life course of individuals, particularly physical and mental health as well as disability and mortality. The empirical evidence I gather shows that early childhood health matters for the achievement of, or social accession to, adult social class positions. Even if the magnitude of associations is not overwhelming, it is not weaker than that found between adult social accession and other, more conventional and better-studied individual characteristics, such as educational attainment. It is very likely that the evidence presented in this article grossly underplays the importance of early childhood health for adult socioeconomic achievement.