Problem-solving theory and research were selectively reviewed for possible applications in behavior modification. Problem solving was defined as a behavioral process which (a) makes available a variety of response alternatives for dealing with a problematic situation and (b) increases the probability of selecting the most effective response from among these alternatives. Five stages of problem solving were identified: (a) general orientation or "set," (b) problem definition and formulation, (c) generation of alternatives, (d) decision making, and (e) verification. Training in problem solving was conceptualized as a form of self-control training, that is, the individual "learns how to solve problems" and thus discovers for himself the most effective way of responding. General guidelines are presented for clinical application with cases characterized by a deficit in effective behavior and its emotional consequences.