IN SPITE of intense research activity and interest in childhood schizophrenia and early infantile autism, there has been little attention paid to the actual incidence or prevalence of these disorders. Most accounts have been anecdotal or have been reported from a single institution or from a single author's caseload and experience. This study seeks to identify the incidence and prevalence of childhood schizophrenia and infantile autism in an entire state population age 12 and under by identifying nonduplicated cases coming to attention or under treatment for a five-year period (1962 to 1967) in Wisconsin's community mental health clinics, state and county mental hospitals, colonies, and training schools, Children's Diagnostic Center, Children's Treatment Center, and University Hospitals. These cases then form a large sample from a variety of clinical settings for comparison with previously reported studies on descriptive parameters such as