Dr. Costello presents a new method of conceptualizing personality disorders similar to the symptom approach he developed in his several previous books. He proposes that what has been gained through the knowledge of the nature of specific personality characteristics should be used to investigate their interrelationships. In this way, practitioners are likely to obtain more valid diagnoses along with an understanding of the processes underlying the conditions diagnosed. Deals with disorders in terms of observable behaviors rather than inferential nosologies such as in the DSM.