Reviews the logic of trait explanation and presents a general model of the person in which personality traits are hypothetical constructs regarded as basic dispositions. In interaction with external influences, notably shared meaning systems, traits contribute causally to the development of habits, attitudes, skills, and other characteristic adaptations. In this model, action and experiences can be explained directly or proximally in terms of the interaction of the immediate situation with the individual's characteristic adaptations, and indirectly or distally in terms of underlying personality traits.