The adult mammalian neocortex, the major region of the cerebral cortex, is divided into functionally specialized areas, defined by distinct architecture and axonal connections. Extrinsic influences, such as thalamocortical input, and genetic regulation, intrinsic to the dorsal telencephalon, control the gradual emergence of area-specific properties during development. Major recent advances in this field include: the first demonstration of the genetic regulation of arealization, implicating the transcription factors Emx2 and Pax6 in the direct control of area identities; and the demonstration of the potential role of the signaling protein, fibroblast growth factor 8, in the early patterning of arealization genes, such as Emx2.