Participants in this single-blind study will be randomly assigned to receive 20 sessions of either broad (enhanced) or focused CBT. Participants will meet with a therapist once or twice weekly until 20 sessions have occurred. Broad CBT will address symptoms of BN, as well as those of the personality disorder. Focused CBT will concentrate only on BN symptoms. Before treatment begins, participants will complete a set of questionnaires pertaining to their experiences with BN, depression, anxiety, and interpersonal relationships. The questionnaires will be used throughout the study to assess participants' progress. Participants will also attend a clinical interview lasting approximately 3.5 hours. Questions will concern BN, other eating disorder symptoms, depression, anxiety, and interpersonal relationships. Blood samples and vital signs will also be taken at the time of the clinical interview and as needed later in the treatment process.