Constraint-induced (CI) therapy is a term given to a family of efficacious neurorehabilitation treatments including to date: upper extremity CI movement therapy, lower extremity CI movement therapy, pediatric CI therapy, and CI aphasia therapy. The purpose of this article is to outline the behavior analysis origins of CI therapy and the ways in which its procedures incorporate behavior analysis methods and principles. The intervention is founded on the concept of "learned nonuse", a mechanism now empirically demonstrated to exist, which occurs after many different types of damage to the central nervous system (CNS). It results from the dramatic alteration of the contingencies of reinforcement that results from substantial CNS damage and leads to a greater deficit than is warranted by the actual damage sustained. CI therapy produces a countervailing alteration in the contingencies of reinforcement. The intervention has been used successfully to substantially improve motor deficits after stroke, traumatic brain injury, spinal cord injury, multiple sclerosis, with cerebral palsy in a pediatric population, and for language impairment in poststroke aphasia. The protocol of CI therapy consists primarily of standard behavior-analytic methods. It produces a marked plastic brain change that is correlated with its therapeutic effect, and therefore provides an example of the way in which behavior change can contribute to a profound remodeling of the brain. CI therapy may be viewed as an example of behavioral neurorehabilitation. (Contains 3 figures.)