The specialized receptive field properties of superior colliculus cells are believed to be dependent upon cortical influences. Yet despite a corticotectal projection near the time of birth and adult-like cortical cells at the beginning of the second week of life, specialized properties do not appear in many superior colliculus cells until quite late in postnatal development. We now report that this apparent conflict is due to the protracted functional maturation of the corticotectal system.