Disorders provide an important source of information in developing theories of normal categorisation. Disruption in categorisation in individuals diagnosed with schizophrenia has been widely evidenced. However, findings are often contradictory and subject to significant confounds. In the present study 35 high schizotypes and 35 low scorers completed a semantic categorisation task and a borderline categorisation task, with measures of category membership judgment, similarity and response time being taken. Results revealed that high schizotypes made significantly fewer positive category membership judgments than low schizotypes (p = .003) and suggest that different theoretical explanations may be required to explain the categorisation of high and low schizotypes. Explanations in terms of theories of normal categorisation are developed.