In most talk therapies for outpatient adults, the therapist has no contro over the client's daily life or contingencies outside the treatment session. The fundamental theoretical issue facing the behavior analyst is, "How can the talking that goes on during the session help the client with problems that occur outside the session in the client's daily life?" An historical analysis and the application of verbal behavior principles are used to answer the question and form the basis of clinical behavior analysis (CBA). The implications of CBA range from providing a theoretical base for psychotherapy to suggesting new forms of treatment.