RESUMEN
In recent years, many competing concepts of schizophrenia have been described, each with some evidence to support its value. Even more recently, specific evaluation methods and diagnostic criteria have been developed so that each of these concepts can be reliably diagnosed. Because of these advances, it is important for the clinician and investigator working with schizophrenics to recognize the way in which the various concepts are reflected in the several reliable approaches now available for diagnosis and to be able to choose a method of diagnosis that is most likely to be useful. We describe the competing conceptualizations and the related diagnostic approaches that have been developed, and then outline the differences and similarities and advantages and disadvantages of these approaches. An orientation toward using these approaches for diagnosing schizophrenia is suggested that permits employing several approaches simultaneously to provide the greatest chance for determining important relationships among diagnostic, clinical, and research variables.