Much controversy remains around the question: How many different types of psychotic illness are there? Applying latent class analysis to detailed assessments of probands with psychotic and affective illness from a population-based psychiatric registry in county Roscommon, Ireland, Kendler et alArticle found 6 classes: classic schizophrenia, major depression, schizophreniform disorder, bipolar/schizomania, schizodepression, and hebephrenia. These classes differed on many historical and clinical variables and on the pattern of psychopathology in relatives. These results suggest a relatively complex typology of psychotic syndromes more consistent with the DSM-IV approach than either with a unitary model or with the Kraepelinian dichotomy. A Commentary by CrowArticle and Reply Commentary by KendlerArticle are included.