Although the majority of epileptics who are well controlled on medication do not show significant evidence of psychopathology, a subset of epileptics have serious psychiatric disturbances. Risk factors for the development of psychopathology appear to include poorly-controlled seizures, a long duration of seizure disorder with onset in childhood, seizure focus in the temporal lobe, bilateral or multiple discharges on EEG, and structural lesions. All of these factors appear to put the patient at greater risk of brain dysfunction, possibly because of the disruption of limbic functions associated with behavior and personality. The onset of seizures in childhood is likely to affect the development of personality and social functioning adversely. Although not a focus of this article, premorbid personality, psychologic reactions to having epilepsy, and the social problems accompanying the disease are likely to contribute greatly to the development of psychopathology. The development of psychiatric disorders in epilepsy thus appears to be a complex, multifactorial process. No single factor, such as seizure type, EEG findings, lateralization, pathology, or demographic variables is likely to be explanatory. Recent research has focused on accounting for many of these factors, and future investigations should shed further light on why some epileptics develop psychiatric problems and how best to treat these disorders.