Abstract
The four most inactive schizophrenic patients were selected by an observational technique from a ward of severely ill chronic patients. Of the four, two patients repeatedly refused to accept any dispensable rewards. Applying Premack's principle of reinforcement, consistent work behavior was shaped and maintained, using sitting as the reinforcer. The results indicate that the strict application of Premack's principle may have considerable therapeutic potential for those patients who, by refusing all tangible rewards, fail to respond to a reinforcement regime.