This issue of FOCUS, devoted to personality disorders, is an attempt to bring readers the latest information emerging from the study of these axis II conditions. In his comprehensive review of the field of personality disorders, John Oldham traces the history of the diagnosis up to the current controversy surrounding the dilemma of categorical versus dimensional classifications. He points out that the current diagnostic system presents a host of problems, including the fact that there is extensive overlap in diagnostic criteria, leading to the common observation that one patient can meet criteria for several personality disorders. He also reviews the impressive breakthroughs in neurobiological research on personality disorders using imaging techniques. This growing body of empirical work establishes unequivocally that personality disorders are biopsychosocial entities requiring a comprehensive approach to diagnostic understanding and treatment. Finally, he succinctly reviews the data from randomized controlled trials suggesting that specific psychotherapeutic interventions are highly efficacious in treating borderline and cluster C personality disorders, at times in combination with a target-symptom approach to pharmacotherapy.