Stress hormones, particularly glucocorticoids (eg, cortisol) and the processes that regulate them are part of the story of how early experiences shape brain development. This article reviews the research on the impact of glucocorticoids on the brain. The authors then describe the psychological and social processes that reduce stress hormone responses to threatening and painful procedures. Finally, they review the literature on cognitive and emotional effects of synthetic glucocorticoids. They attempt to provide a succinct overview of this complex area, pointing out where improvement in understanding and management of stress hormones early in development may improve medical and behavioral outcomes.