The term Afro-Caribbean is used to describe black people of Caribbean origin in Britain. Migrants from the Caribbean, their children and their children's children are all covered by this term. The group as a whole is reported to have a higher incidence rate of schizophrenia than white groups, (King et al 1994), and British-born children of Caribbean parents have an even higher rate (Harrison et al, 1988). These reports have led to the hypothesis that Afro-Caribbeans may have a special vulnerability to schizophrenia. While limitations to these studies have been identified, (Wessly et al 1991) none has sought to question the use of the term Afro-Caribbean as a valid and reliable ethnic grouping. If we are to be able to produce good hypotheses for the aetiology of the reported increases in incidence, or to produce research which is useful to Black and ethnic minority groups, we need a clear understanding of the people under study.