This study seeks to examine the efficacy of hydrocortisone administration in the augmentation of the therapeutic effects of Prolonged Exposure (PE) therapy, an empirically tested treatment shown to be effective in the the treatment of posttraumatic stress disorder (PTSD). The augmentation builds on both the translation of neuroscience findings demonstrating the effects of glucocorticoids (GCs) on learning, and on empirical clinical findings from other investigators demonstrating beneficial effects of GCs in reducing traumatic memories in trauma-exposed persons.