Purpose: In a nationally representative population-based study in England, we estimated the burden of psychiatric and neurodevelopmental comorbidities in people with epilepsy. We investigated whether any overrepresentation of comorbidities could be explained by epilepsy being a chronic medical or neurologic condition, or by the confounding effect of demographic and socioeconomic factors or other health conditions. Methods: The Adult Psychiatric Morbidity Survey 2007 comprised detailed interviews with 7,403 individuals living in private households in England. Doctor-diagnosed epilepsy (and asthma, diabetes, and migraine, chronic conditions for comparison) was ascertained by self-report, and extensive diagnostic and screening interviews were used to assess psychiatric and neurodevelopmental conditions. Key Findings: The estimated lifetime prevalence of epilepsy in the adult (≥16 years old) population of England was 1.2% (95% confidence interval [CI] 1.0-1.5). Almost one-third of the people with epilepsy had an International Classification of Diseases, Tenth Revision (ICD-10) anxiety or depressive disorder (compared with one in six people without epilepsy). Among these, social phobia and agoraphobia, generalized anxiety disorder, depression, and measures of suicidality had strong associations with epilepsy, which remained robust after accounting for potential confounders. These associations were consistently stronger than those in people with asthma or diabetes, and similar to those in people reporting migraine or chronic headaches. Epilepsy was also strongly associated with autism spectrum disorders (odds ratio [OR] 7.4, 95% CI 1.5-35.5) and possible eating disorders, and these associations were not evident in people with asthma, diabetes, or migraine. Significance: Psychiatric and neurodevelopmental conditions were overrepresented in people with epilepsy. These associations were stronger than with other nonneurologic chronic conditions, and not explained by confounding. Some overlap in the psychopathology observed in epilepsy and migraine cannot rule out the presence of common pathways of psychiatric comorbidity in neurologic conditions. However, associations of epilepsy with conditions such as autism spectrum disorders point to comorbidities specific to epilepsy that may not be shared by other neurologic conditions.