Patients with borderline personality disorder (BPD) will be provided with an empirically supported form of psychotherapy for BPD patients called transference-focused psychotherapy (TFP) and medication treatment, if indicated. The primary goal of the current study is to detect changes in psychological, psychosocial and work functioning over the course of 18-months of TFP. Previous research has shown that TFP is an effective treatment for BPD over the course of one year, significantly reducing symptoms. An 18-month treatment period will most likely allow patients to achieve significant and lasting gains in work and psychosocial functioning. Each patient will be assessed prior to (baseline), at 3-month intervals throughout, and at the termination of the 18-month treatment period for symptoms, vocational status, and psychosocial functioning. In addition, patients and therapists will complete self-report measures every three months about the therapeutic relationship. After the 18-month treatment period, a final, brief assessment of vocational status, symptoms, and psychosocial functioning will occur.

The therapists doing TFP are professional psychiatrists, psychologists, and social workers who have been trained by Dr. Otto Kernberg in this special form of psychotherapy. In this therapy, the patient and therapist meet in the therapists' private office for 50-minute sessions two times a week on a weekly basis (except for vacations) for 18 months.

Hypothesis: It is hypothesized that patients in Transference Focused Psychotherapy (TFP) will manifest differential responses to the treatment, depending upon pre-treatment patient psychological and psychiatric characteristics. The investigators expect that some patients will show significant positive changes in symptoms, work, and social functioning at the end of 18 months, and that these positive changes will manifest in psychological and neuropsychological measures. The investigators will investigate the pre-treatment psychological variables (e.g. trait sociability, constraint, and negative affect) and neuropsychological functioning (executive attention, capacity to inhibit behavior, memory functioning) that will be predictive of patient improvement with treatment at the end of 18 months. By the end of the treatment, the investigators expect some patients to approach normal levels of enjoyment and enrichment of their experiences in work and social functioning. As all analyses will occur at the end of the study, response to TFP will not be assessed during the course of treatment. Therefore, patients will not be moved to a different intervention during the course of the study.

Research Question: The investigators have found in our pilot work that symptom change occurs in the first 12 months of TFP followed by substantial work and psychosocial changes in subsequent months. The primary goal of the current pilot project is to demonstrate that TFP over an 18-month treatment period is associated with significant improvement in work and intimate relations, reflecting significant personality changes that should enhance patients' overall effectiveness and gratification in their lives.