Most studies examining the comorbidity of epilepsy and psychiatric disorders have been cross-sectional in hospital- and institution-based populations. This chapter summarizes community-based studies of psychiatric comorbidity in epilepsy. While cross-sectional studies of psychiatric disorders and epilepsy provide valuable public health information and inform epileptologists and psychiatrists, they have significant limitations. Over the past 20 years, a body of work has emerged examining whether specific psychiatric disorders are associated with an increased risk for developing epilepsy, and assessing the incidence of psychiatric disorders after the onset of epilepsy. Attention-deficit hyperactivity disorder (ADHD) and depression is associated with an increased risk for developing epilepsy. Several studies show that a history of major depression is associated with an increased risk for developing unprovoked seizures. Studies examining the time order of the relationship between psychosis or schizophrenia and epilepsy have all been conducted in population-based registries.