The human neocortex is a highly sophisticated and organized brain structure that is thought to mediate some of the most complex cognitive functions in humans including language and abstract thought. As such, environmental and genetic insults to its normal structure or function can result in devastating neurological conditions including severe epilepsy and intellectual disability. Malformations of cortical development are an increasing collection of disorders that cause neocortical abnormalities due to impaired developmental processes. One recently identified disorder in this class is a thin lissencephaly variant (TLIS) associated with several mutations in the C-terminus death domain of the caspase-2 activation adaptor CRADD (also known as RAIDD). Beyond this, little is known about the mechanism underlying TLIS pathophysiology despite an increasing number of identified individuals suffering from it. In order to better understand this disorder, as well as the normal developmental mechanisms that are impaired in its pathogenesis, I have developed and characterized three murine models by introducing one of a number of different genetic perturbations associated with TLIS. These animal models show behavioral and biochemical abnormalities similar to those seen in human TLIS subjects. Focusing future studies on the developmental processes that underlie differences seen in these mouse models could greatly inform understanding of disease mechanism in humans and assist in the development in therapeutic interventions. My work presented in this dissertation thus effectively establishes a translationally relevant animal model of TLIS.