Cognitive and behavioural comorbidities are often seen in children with epilepsy, and are more common and severe in refractory epilepsy. These comorbidities are associated with worse quality of life, increased behavioural and language problems and worse social skills, all of which adversely affect long-term psychosocial functioning. To enable early intervention and therapy, children and teens with epilepsy should be periodically screened for cognitive comorbidities. The location of the epileptic focus can, to a certain degree, predict the type(s) of comorbidity; however, the spectrum of disability is often broad, presumably because focal perturbations can cause network dysfunction. Comorbidities often result from underlying structural or functional pathology that has led to seizures. In selected cases, therapy targeting the underlying cause, such as the ketogenic diet for GLUT1 deficiency syndromes, may be remarkably effective in ameliorating both seizures and cognitive concerns. In many cases, however, cognitive impairment persists despite seizure control. In epileptic encephalopathies, frequent seizures and/or interictal epileptiform abnormalities exacerbate neurocognitive dysfunction, owing to synaptic reorganization or impaired neurogenesis, or to other effects on developing neural circuits, and prompt initiation of effective antiepileptic therapy is essential to limit cognitive comorbidities.