Although in the Diagnostic and Statistical Manual of MentalDisordersof the American Psychiatric Association

(DSM) schizophrenia is listed as a psychotic disorder, DSM criteria include negative symptoms and psychomo-tor abnormalities as well as hallucinations, delusions, and disorganization. In recent years, the concept that cognitive impairment—problems in memory, attention, executive function, etc—is also inherent to schizophrenia is gaining acceptance, and cognitive markers are now used as endo-phenotypes to explore the genetics of schizophrenia. If the concept of schizophrenia extends beyond psy-chosis and negative symptoms, how far should it go? What are the boundaries of schizophrenia? In this theme issue, the authors explore that issue. Three of the articles review neuropsychiatric problems other than psychosis and negative symptoms. Dickinson and Harvey1 argue that within schizophrenia, cognitiv