Cerebral cortex development is a complex process, encompassing several relevant aspects, such as telencephalic regionalization, cortical arealization, cell cycle regulation, neuronal differentiation, neuronal migration, cortical wiring. Comprehension of their genetic control is a formidable task, fascinating per se and because providing clues about aetiology of a number of neurological cortical disordes affecting human patients, for which a neurodevelopmental origin has been postulated but not yet clarified. Our group is traditionally interested in genetic control of early steps of normal corticogenesis; more recently, we started to model in the mouse a rare human syndrome, the Williams-Beuren syndrome, including cortical dysplasias and a peculiar, aberrant cognitive-behaviourial profile.