The relation between premorbid social competence and outcome was examined with 381 male state hospital patients in four diagnostic categories: schizophrenia, affective reaction, psychoneurotic disorder, and personality disorder. Outcome was assessed using the measures of length of initial hospitalization, total length of rehospitalization, and number of readmissions. The follow-up period was 3 years after discharge from the first hospitalization. On all outcome measures, higher social competence was significantly related to favorable outcome. The four diagnostic groups differed significantly in social competence level, but no evidence was found to indicate that the social competenceoutcome relation was influenced by diagnosis. Results were interpreted as consistent with a developmental formulation and as indicating that the relation between premorbid social competence and outcome is not unique to schizophrenia but obtains over a broad range of diagnoses.