In this laboratory we have developed a set of techniques that randomized controlled studies indicate can substantially reduce the motor deficit of patients with mild to moderately severe chronic strokes. The techniques, termed Constraint-Induced Movement therapy (CI therapy), in-volve motor restriction of the less-affected arm while at the same time intensively training the more-affected arm. The intervention was derived directly from basic research with monkeys. The primary difference between CI therapy and conventional physical therapy is in the duration and intensity of the treatment. The greatly improved extremity function produced in the laboratory transfers to the activities of daily living outside the clinic. Treatment gains persisted for the two years tested. Converging data from seven experiments has shown that CI therapy produces massive alterations in brain organization and function correlated with the large improvements in motor ability that it produces.