Cortical dysgenesis (CD) describes a wide spectrum of brain anomalies that involve abnormal development of the cerebral cortex. There is a strong association between CD and epilepsy, and it comprises a significant proportion of children and adults whose epilepsy cannot be controlled with medications. There has been intense effort to define the relationship between CD and epilepsy so that more effective therapies can be devised. These efforts have ranged from detailed study of people with CD and epilepsy from a clinical standpoint to single-cell analysis of mRNA expression and postsynaptic receptor function. Animal models have also been developed to mimic certain aspects of CD in a situation when quantitative, controlled, and interventional experiments can be performed that would not be possible in a clinical setting. This review will give an overview of human CD syndromes and their causes, when possible, and describe some specific abnormalities in dysplastic cortex that may underlie its epileptogenic potential. It will also review several animal models of CD that have been studied mechanistically from the standpoint of epileptogenesis. In conclusion, some general trends will be proposed based on human and animal studies to encapsulate our current understanding of CD and how it causes epilepsy.