Longitudinal evaluations were conducted on 61 adults who were referred to a Mood Disorders Unit with a history of depression (all index episodes reached criteria for DSM-III-R major depression or dysthymia) and who had completed a cognitive behavioural therapy group either on its own or in combination with an assertion training group. Assessment of personality was made using DSM-III-R Axis II personality disorder categories. These categories were aggregated to form three groups: (i) no personality disorder; (ii) Cluster B (dramatic-erratic); and (iii) Cluster C (anxious-fearful), and were used to identify responsiveness to treatment and outcome at long-term follow-up. A battery of self-report measures were administered pretreatment, posttreatment and at long-term follow-up (1–3 years later). Both groups showed significant improvements in mean scores during treatment and these gains were maintained over the follow-up period. However, improvement in those patients without personality disorders was greater at posttreatment and at long-term follow-up, both in level of depressive symptomatology and proportion of cases meeting criteria for recovery. The treatment implications of these results are discussed.