The development of the cerebral cortex is extremely complex but can be divided into different, partly overlapping stages. Interference with one or more of these processes by genetic or external factors may result in malformations of cortical development (MCD). The most prevalent MCDs include focal cortical dysplasia, polymicrogyria, periventricular heterotopia, the cortical tubers of tuberous sclerosis complex, and malformations of the lissencephaly/subcortical band heterotopia spectrum. Together, these malformations represent approximately of all MCDs diagnosed in childhood. MCDs are an important cause of mental and motor impairment, severe epilepsy, learning disorders, and autism. For the large majority of patients with MCDs, the exact etiology of their disorder is still unknown, and counselling of parents and close relatives remains limited. Patients require a lifelong multidisciplinary follow-up and treatment is restricted to symptom relief. The characterization of the genetic causes of MCDs currently represents the only way to prevent recurrence.