The onset of adolescence, and more specifically the advent of pubertal maturation, represents a key developmental window for understanding the emergence of psychopathology in youth. The papers in this special section examine normative differences in the neurobiology of stress and emotional functioning over the peripubertal period. The work in this special section helps to fill in gaps in our understanding of key mechanisms that may contribute to increased vulnerabilities in behavioral and psychiatric morbidity during this developmental period.