Until only very recently, the occurrence of schizophrenia in childhood and early adolescence had been largely neglected. Improved diagnostic formulations have resulted in clarification of the boundaries between childhood schizophrenia, other psychotic disorders, and pervasive developmental disorder. The study of schizophrenia in childhood or adolescence provides a unique opportunity to examine illness characteristics in the absence of the confounds of substance abuse illness, chronicity, and medication effects. Additionally, current etiopathologic models of schizophrenia can be tested in this patient subgroup.