This is the first of a series of volumes in which the author will present the results of an extensive study of the postnatal development of the human cerebral cortex, beginning at the time of birth. Here he discusses the condition of the neurons in the cortex of the full-term fetus immediately after birth. No such comprehensive study of the development of the cerebral cortex has been heretofore attempted. The definitive cytoarchitectonic pattern of the cerebral cortex is already established in the normal full-term infant at the time of birth. Distinct regional differences in degree of development of the neurons and myelination of the fibers are clearly apparent. In general, the primary efferent area in the gyms centralis anterior, and the primary afferent areas in the gyms centralis posterior, the area striata, the hippocampus, gyrus temporalis transversus anterior, and the gyms cinguli are foci of development in their respective lobes, and in each lobe there is a gradual decrease in differentiation away from these centers.