The American Psychiatric Association's DSM-IV criteria for schizoaffective disorder persisted for 19 years (1994–2013). Clinicians adequately trained in diagnosis used the schizoaffective diagnosis too often, largely because the criteria were poorly defined, ambiguous, and hard to use (or poorly operationalized). Poorly trained clinicians used the diagnosis without making necessary exclusions of common causes of psychosis, including some prescribed psychiatric medications. Specialty books written by experts on schizoaffective disorder have existed for over eight years before DSM-5 describing the overuse of the diagnosis.