In this study we investigated the putative role of cognitive dysfunction, diagnosis (schizoaffective versus schizophrenia disorder), and alcoholism as risk factors for suicidal behavior among individuals with DSM-IV schizophrenia or schizoaffective disorders. Subjects received cognitive tests and medical records were reviewed for evidence of a history of suicide attempts or suicidal ideation. Discriminant analysis was used to identify cognitive test performance measures that distinguished those with versus those without suicidal behavior. None of the cognitive measures discriminated between the two groups. The rates of suicidal behavior (suicidal ideation and suicide attempts) did not differ between participants with versus those without comorbid alcohol use. An association was found between suicidal behavior and the diagnosis of schizoaffective disorder. It was concluded that the history of prominent mood syndromes characteristic of schizoaffective disorder contributes to increased risk of suicidal behaviors. Cognitive dysfunction and/or alcoholism did not contribute additionally to risk in this study.