ABSTRACT
The traditional concept of the diagnosis of specifi c language impairment (SLI) was that it was a specifi c diagnostic category involving a pure language problem. The presumption was that it was both separate from normal variations in the timing of language acquisition and separate from other developmental and psychopathological disorders. Current offi cial classifi cation systems such as DSM-IV (American Psychiatric Association, 2000) and ICD-10 (World Health Organization, 1996) use the terminology of the overarching concept of developmental disorder. The implication of that term is that SLI is thought to be crucially different from acquired disorders
of language. Both classifi cation systems go on to make categorical distinctions among several supposedly different types of SLI.
