This chapter reviews the patterns of neuropathologic abnormality encountered in cortical resections performed for the treatment of infantile spasms (ISS) in the broader context of the larger "universe" of neuropathology seen in the central nervous system of infants with this syndrome as well as older children with intractable epilepsy. Although destructive lesions (encephalomalacia), Sturge-Weber-Dimitri syndrome, and even neoplasms can cause ISS, its most common neuropathologic substrate is cortical dysplasia (CD), representing the result of aberrant neuronal migration to the neocortex from the germinal matrix. Ways to recognize CD morphologically and assess its severity are reviewed, as are special stains and immunohistochemical methods that may be useful in confirming the diagnosis. The similarity and relationship between (sporadic) CD and tubers of tuberous sclerosis are discussed. Future potentially fruitful research directions aimed at refining the clinicopathologic analysis of the role of CD in ISS and epilepsies of older children are briefly considered.