This update of the personality disorders section of Gabbard's Treatments of Psychiatric Disorders was prepared against the backdrop of three significant advances in our understanding about personality disorder psychopathology and treatment. The first of these is that longitudinal research has shown that personality disorders undergo substantial improvements (Skodol et al. 2005; Zanarini et al. 2005). The second development is the growing recognition that personality disorders have significant genetic determination (Siever et al. 2002; Torgersen et al. 2000). The third advance is that psychoanalytic psychotherapy has been manualized in a way that permits testing and replication.