This introduction describes a thcory of personality originally formulated by John W. Gittinger and indicates how his theory can be applied to the understanding of personality development and to the prrdiction of behavior. One of the major strengths of Gittinger's approach is that it permits predictions based on readily obtainable behavioral or psychological test data. His formulations also have a number of other advantages from both the pr:tcticnl and the theoretical points of view.From the viewpoint of practical application, the way in which the theory orders data permits comparatively specific predictions concerning behavior and experience. With regard to behavior, the Personality Assessment System (PAS) : (a) Indicates the kinds of internal and external cues to which the individual is most likely to respond; (b) suggests the types of stimuli that are most likely to produce behavioral change; (c) provides an understanding of the inter-, intra-, and impersonal environments in which a person is most likely to function efficiently; and (d) offers insight into what constitutes stress and predicts probable behavioral response to such stress, including maladjustments, should they occur.In the area of experience, the PAS offers a method for obtaining specific clues to personality structure and functioning. Thus, the PAS: (a) allows for direct inferences concerning an individual's primary response style; (b) suggests the quality of the compensations and modifications he has achieved in response to social and environmental pressures ; (c) provides an understanding of personality development in terms of thr interaction of primary structure, environmental pressures, and adaptive tendencies; (d) offers a procedure for evaluating the surface or contact personality developed over time; and (e) makes possible the assessment of the fundamental discrepancies between the surface personality and the underlying personality structure-discrepancies that typically produce tension, conflict and anxiety.PAS thus provides insights contributing to clinical practice in that a distinctive pattern of strengths and weaknesses can be derived for each person. At the same time, the system allows objective comparisons among the personality features of different Ss and groups, thereby offering a suitable framework for behavioral research and permitting definitive investigations into personality structure and function.Krauskopf and D a v i~( 3~. pp This theory is the result of a long term effort of several people but (is) primarily the insight of one man. . . . Anyone who has worked in applied psychology has met insightful, sensitive clinicians. Some seem to be nearly magical point out: *The authors thank Walter P. Pasternak for his editorial assistance in the preparation of this pa er. Drs. Dennis J. Nauman and Marshall N. Ileyman of Psychological Assessment Associates, E&ard V. Malcom, formerly VA Hospital T o y Maine, Charles J. Krauskopf, University of Missouri at Columbia, and David H. Saunders, niversity of Colorado, have also made valuable ...