Personality disorders have been recognized as categories of psychiatric illness, and still need to be better defined. This book interprets the personality disorders as products of the interaction between social influences and other aetiological factors as part of a broad biopsychosocial model, and explains how personality traits develop into personality disorders. Strongly oriented towards recent empirical findings, the author argues that although biological, psychological and social factors are all necessary, none of them is by itself sufficient to produce a personality disorder. This basic model is also a model of treatment, in which biological, experiential and social factors should all be addressed in therapy and his treatment recommendations focus particularly on social adjustment through the adaptive use of personality traits.