During the last 20 years, an emerging body of data has delineated critical variables controlling the acquisition and retention of aversive experiences across ages. Focusing an the rat as subject organism, the behavioral literature on task- and age-specific findings is reviewed. Response inhibitory deficits in younger subjects are related to augmentation of stimulus control through discrimination training and reinstatement of components of original learning. Somewhat parallel and complementary to studies of behavioral development, advances in the neurophysiology and neuroanatomy of cortical functions have indicated the critical role of the prefrontal cortex in acquisition and retention of aversively motivated instrumental responses. Several studies of prefrontal damage administered at varying ages reveal the importance of neural development in both performance deficits as well as recovery of function. These preliminary experiments are discussed in light of constraints from appropriate cortical influences in consideration of the ontogeny of fear.