Ego Development and Psychopathology presents an original theoretical underpinning for classification and interpretation of the major mental disorders, one based largely on the author's clinical experience. Ausubel's central thesis is that the most significant and crucial factors predisposing persons to mental disorders are critical developmental defects that arise at vital transitional phases of ego development. He sees both normal and pathological personality functioning as most cogently explained in terms of an individual's ego structure at a given point in the life cycle. Ausubel relates his developmental theory to the phenomenology and related clinical problems of psychiatric diagnosis. He classifies mental disorders in terms of their developmental history. Such factors, in his opinion, offer the most precise delineation of etiological, functional, and phenomenological similarities and differences among the various psychiatric syndromes. He provides an overview of ego development, as well as major variants of the norm. He also discusses development of conscience and moral values, as well as psychopathological considerations that follow from deficiencies, defects, failure, and distortions in ego development. He examines at length classification of mental disorders, such as anxiety states, psychotic depression and mania, schizophrenia, autism, antisocial and narcissistic personality disorders, and defense mechanisms. Ausubel is careful to point out that ego development is not the only significant determinant of normal and aberrant personality. Genetic predispositions, situational stress, and sociocultural factors must always be taken into consideration since mental disorder is always a product of multiple causality. However, he believes ego development is by far the most critical factor, and hence offers the most for classification of mental illness. This intriguing study will be of interest to professionals as well as educated and concerned practitioners in the fields of psychology, psychiatry, psychoanalysis, child psychotherapy, and social work.