The elimination or modification of unwanted behavior is a frequent goal of psychotherapy. Although assessment of psychotherapeutic effectiveness is an extremely complex matter, there seems to be rather general agreement that orthodox clinical procedures have not proven very effective in dealing with adolescent behavior disorders. In 1958 a small clinical research project studying the dynamics of hostility hired seven adolescent male delinquents to participate in interviews and to take a series of psychological tests. It was hypothesized that therapeutic intervention which provided planned differential consequences for typical interview behaviors would result in different "treatment" outcomes. Since the frequency of positive statements and of attendance behavior was altered with an average of only six reinforcement attempts, one of the issues raised by the study would seem to be the adequacy of a "reinforcement" interpretation of the results. The failure to obtain a more profound reduction in hostile statements or clearer transfer effects is believed to be a result of procedural inadequacies.