The subjects of this study were 19 children and 11 adolescents who had been psychotic since childhood and who satisfied DSM-III criteria for schizophrenia except for the stipulation that a "deterioration from a previous level of functioning" must have occurred. Seven subjects had had documented signs of psychosis before the age of 30 months. The presence of thought disorder precluded giving these 7 subjects the diagnosis of early infantile autism. The authors argue that only symptoms and signs, not age at onset, can define a disorder. They also emphasize that in children and adolescents, developmental issues influence the clinical presentation.