Organizing a vast body of scientific literature, this indispensable book presents the state of the art in understanding borderline personality disorder (BPD) and distills key treatment principles that therapists need to know. Rather than advocating a particular approach, Joel Paris examines a range of therapies and identifies the core ingredients of effective intervention. He offers specific guidance for meeting the needs of this challenging population, including ways to improve diagnosis, promote emotion regulation and impulse control, maintain appropriate therapeutic boundaries, and deal with suicidality and other crises. Highly readable, practical, and humane, the book also explains the latest thinking on the causes of BPD and how it develops.