The diagnosis of autism, although a source of discussion and occasional controversy, has consistently included poor communication as an essential component. Both the text revision of the fourth edition of the "Diagnostic and Statistical Manual of Mental Disorders" (American Psychiatric Association, 2000) and the 10th edition of the "International Classification of Diseases" (World Health Organization, 1993) cite qualitative impairments in communication as central diagnostic criteria. Some researchers have even indicated that the communication deficits associated with the disability of autism are its most significant deficit (Rutter & Schopler, 1988).