Many patients with schizophrenia show clinical signs of frontal lobe dysfunction, including blunted affect, difficulty with problem solving, and impoverished thinking. The authors present cytoarchitectural, neuropsychological, and functional neuroanatomical evidence of frontal abnormalities from recent studies of frontal dysfunction in schizophrenia. It is suggested that the failure of intracortical connectivity of the prefrontal cortex accounts for both cognitive and psychotic manifestations of this illness.