Classical lissencephaly is a human developmental brain disorder characterized by a paucity of cortical gyration and thickening of the cortical gray matter, leading to severe epilepsy and mental retardation. Loss-of-function mutations in the microtubule-associated protein encoding genes, PAFAH1B1 (encoding the protein LIS1), DCX and TUBA1A have been implicated in the pathogenesis of the condition. Animal models are required to understand the basis of this disease, which is a challenge, given that mice normally have a smooth cortex. Recent advances toward this goal have come from stepwise reduction in gene function, deletion of redundant genes and acute gene inactivation using short hairpin RNA (shRNA). These approaches have implicated genes that regulate the microtubule cytoskeleton during neuronal division, migration and maturation.