Behaviorism has long considered explanations and treatment of psychopathology. Miller and DoUard (1941) began to translate psychoanalytic into behavioral concepts. Skinner’s Walden Two (1948), Science and Human Behavior (1953), and Beyond Freedom and Dignity (1971) developed that approach and addressed the conceptualization of psychopathology and its implications for case formulation and treatment. Skinner also expanded on earlier work by offering functional analytic approaches to explaining behavior change that might occur during classic psychotherapy and Rogerian therapy. Functional analytic approaches to psychopathology took off in the 1950s in areas such asmental retardation (Fuller, 1949; Lindsley, 1964a; Risley & Wolf, 1964, 1967; Wolf, Risley, Johnston, Harris, & Allen, 1967; Wolf, Risley, & Mees, 1964), schizophrenia (Ayllon & Michael, 1959; Lindsley, 1956, 1959, 1960, 1963; Lindsley & Skinner, 1954), tics (Barret, 1962), and geriatrics (Lindsley, 1964b) and influenced the development of behavior therapy (Kalish, 1981; Kanfer & Phillips, 1970; Ullmann & Krasner, 1965; Wilson & Franks, 1982). Turkat’s (1985) volume. Behavioral Case Formulation, was notable in illustrating the application of behavior analytic concepts to individual case formulation and in addressing its application to a wide range of clinical problems, such as fear, depression, personality disorders, substance abuse, and problems of later life. This early work formed the basis of subsequent development of functional approached to psychopathology.