Using a subsample of subjects from the Copenhagen schizophrenia high-risk project, this study examined the relationship between ventricular enlargement and prospectively assessed deficits in premorbid school/occupational adjustment. Subjects with enlarged ventricles evidenced poorer premorbid school-occupational adjustment across three times of measurement spanning a period of 10 years. This effect was independent of the age and sex of the subjects and remained significant after controlling for psychiatric diagnosis. The results provide prospective evidence for an association between ventricular enlargement and poor premorbid history.