Van Bilsen, a consultant in cognitive behavioral therapy and clinical psychology, and Thomson (cognitive behavioral therapy, U. of Hertfordshire, UK) outline an approach to treating clients with personality disorders that is based on their analyses of their personal, interpersonal, and societal problems, not a categorical approach that focuses on programmatic and protocolized interventions that fulfill the criteria of a specific diagnosis. They emphasize the development, maintenance, and functionality of the client's problem presentation and detail the theory, practice, and process of cognitive behavioral therapy; core interventions for these clients; how to engage and motivate them; the concept of personality disorders and their diagnostic criteria; the larger context of societal perspectives on deviance; the cost of personality disorders to society; evidence for psychological interventions; and pitfalls.