Psychotherapy has historically been the mainstay of treatment for personality disorder (PD). It remains so. Psychoanalysis was probably the earliest formal treatment for PD, which led to the first clinical descriptions of borderline personality disorder. A parallel but linked development was the application of psychoanalytic ideas in therapeutic communities which have been in existence for over 60 years and remain a treatment context and method for patients with PD. It was only in the 1960s that modified psychotherapeutic treatments were developed. Initially these were based on psychodynamic understanding of PD, but gradually other theoretically and practically driven models have developed, leading to the current situation in which there are behavioural, cognitive, dynamic, and supportive treatments offered in a range of contexts. Some of these methods have more empirical support than others. These methods will be described in this chapter. Psychological therapies for personality disorders take place against the background of the natural course and outcome of the disorder. Until recently, the natural history of personality disorder had not been systematically studied. Several major cohort follow-along studies have yielded surprising data concerning the rate of symptomatic remissions in a disorder that was assumed to have a lifelong course. For example, over a 10-year follow-along period, 88 per cent of those initially diagnosed with borderline personality disorder appeared to remit in the sense of no longer meeting DIB-R or DSM-III criteria for BPD for 2 years. The symptoms that remit most readily, irrespective of treatment, appear to be the acute ones, such as parasuicide and self-injury, which are the most likely to trigger psychotherapeutic intervention. Temperamental symptoms, such as angry feelings and acts, distrust and suspicion, abandonment concerns, and emotional instability, appear to resolve far more slowly. In the Collaborative Longitudinal Personality Disorder Study (CLPS), when remission was defined as 12 months at two or fewer criteria for PDs, over half of BPD and 85 per cent of major depressive disorder (MDD) patients were reported to remit over a 4-year period. Psychosocial functioning recovered far more slowly than acute symptoms. There is a considerable body of literature on psychotherapeutic interventions for personality disorders, but significant evidence for effective treatment remains sparse. Much of the literature is dominated by expert opinion, which is not invariably the most helpful guide. In this chapter, we focus on psychological treatments where at least some evidence for treatment effectiveness exists. The evidence is strongest for borderline personality disorder (BPD). Treatment of some other personality disorders, for example schizoid, narcissistic, obsessive–compulsive, dependent, is evidenced mainly by clinical case reports in which theory is combined with clinical description and where, if outcome is measured at all, it is measured for the purpose of illustration and has little probative value.