Interest in developmental and psychobiological aspects of trauma has grown with recent research in adults with mood and anxiety disorders reporting histories of trauma during childhood. Studies conducted directly in children and adolescents could add much to ongoing research in this area. This review summarizes data in three areas of developmental science that might inform future studies. First, the review briefly summarizes current data on clinical aspects of trauma in juveniles, focusing on associations with psychopathology and moderators of outcome. Second, the review summarizes data from the basic sciences delineating experiential and developmental changes in brain systems involved in threat perception and response. This review incorporates knowledge gained from research examining the effects of rearing manipulations on regulation of the stress response in rodents and primates. Third, the review summarizes data from cognitive neuroscience studies among both adults and children, again focusing on studies examining aspects of the threat response. This summary includes a review from studies in patients with posttraumatic stress disorder.