At least 50-60% of patients with epilepsy develop psychiatric disturbances, particularly mood, anxiety, and psychotic disorders. This article, aimed at the non-psychiatric clinician, reviews the differential diagnosis and treatment of psychiatric disturbances in epilepsy and focuses on the evaluation of psychiatric phenomena relative to the ictal state or the periictal and interictal periods. Pharmacological and non-pharmacological therapies are reviewed. A final section discusses potential interactions between antiepileptic and psychiatric medications.