This is a proof of principle study of mifepristone in the treatment of individuals with BPD and histories of childhood abuse, which aims to translate neurobiological research concerning HPA axis abnormalities in BPD into a novel clinical intervention for patients. This project will also explore an innovative approach to the structure of pharmacotherapy for BPD. Specifically, we will employ the circumscribed (finite) drug administration period used in prior studies of mifepristone in neuropsychiatric illness, which differs from the current clinical practice of indefinite daily usage of medications. We hypothesize that mifepristone will beneficially impact stress response neurobiology and consequently ameliorate associated BPD symptoms.