Explanations of the socioeconomic gradient in health status must account for the observations that the gradient cuts across a wide range of disease processes and is capable of replicating itself on new disease processes as they emerge in society. Understanding this pattern requires an understanding of how human organisms can become generally vulnerable or resilient to disease over time: a huge collation task across different disciplines. The hypothesis that best fits current evidence is that the gradient is an "emergent property" of the interaction between the developmental status of people and the material and psychosocial conditions they encounter over their life course. Within this broad formulation, special attention is given to child development, and the prospect that socioeconomic differences in the quality of early life experiences contribute to subsequent gradients in health status through socioeconomic differences in brain sculpting and the conditioning of host defense systems that depend on communication with the developing brain. The contribution to the gradient in health is theorized to occur through a combination of latent effects, pathway effects, and cumulative disadvantage.