Patients with borderline and other severe personality disorders take up a disproportionate amount of time from psychiatric, accident and emergency and community services. The Edinburgh Project was commissioned to examine the process and outcome of time-limited psychoanalytic psychotherapy with these patients. The project provided once weekly psychotherapy over the period of a year for 19 patients and administered a range of psychometric self-report questionnaires at the beginning of the therapy, monthly and at 3, 13 and 20 months post-therapy. This article presents the findings of those studies and relates them to the psychotherapeutic process. The results suggest that the model adopted in Edinburgh can help to reduce symptoms, acting out, impulsive feelings and behaviours and that these reductions are maintained at post-treatment follow-ups.