Evidence on the maturation of the neocortex was discussed in relation to clinical and behavioral observations on early ego development. The chronological sequence of developing ego functions was discussed following the assumption that neural maturation sets an upper limit to the evolution of mental processes. On the premise that only those mechanisms capable of a partial binding of instinctual energies can be considered ego functions, emerging ego capacities were distinguished from the primitive "precorticate" adaptive mechanisms which characterize the first weeks of life.