There is now sufficient evidence to state that season of birth is associated with the risk for schizophrenia. There is also some evidence suggesting that the season of birth phenomenon may be characteristic of only one subgroup of patients. The objective of this epidemiologic research is to determine whether schizophrenic patients born during the winter months of December, January and February are different from schizophrenic patients born during the other months of the year. The methods of this research are as follows: 1. Schizophrenic patients will be identified by screening several psychiatric facilities in Maryland. 2. Schizophrenics born during the winter months of December, January and February will be compared to schizophrenic patients born during the other months of the year to determine whether they differ in any of the following ways: pre-morbid characteristics, clinical manifestation, and age at first hospitalization.