A reinforcement system based on token reinforcement; the contingencies specify when, and under what conditions, particular forms of behaviour are reinforced. The system is an economy in the sense that tokens may be exchanged for goods and services, much like money is in our economy. This exchange of tokens for a variety of back-up reinforcers ensures that the tokens are conditioned reinforcers. Token economies have been used to improve the behaviour of psychiatric patients, juvenile delinquents, pupils in remedial classrooms, medical patients, alcoholics, drug addicts, prisoners, nursing home residents, and retarded persons.