The purpose of this chapter is to provide information on evidence-based interventions for individuals with a variety of involuntary movement disorders. Involuntary movement disorders affect an individual’s ability to control and modify movement. The movement disorders discussed in this chapter will be limited to those causing dyskinesia or abnormal involuntary movements arising most often from pathology within the basal ganglia, a group of subcortical motor-modulation nuclei. Pathological changes within the basal ganglia can also cause bradykinesia (slowness of movement) and rigidity (joint stiffness) as seen in patients with Parkinson disease. However the focus of this chapter is dyskinesia or involuntary movement. Due to the unique impairments seen in patients with dyskinesia, therapeutic interventions differ from those used with patients who have other movement-related impairments such as spasticity or rigidity (described in Chapter 19), or ataxia (irregular inaccurate movement) (described in Chapter 21). These unique characteristics, as well as their roles in clinical decision-making, will be considered in this chapter. As you read this chapter, refer to Table 20-1 for a brief description of each dyskinesia to be addressed. Refer also to Table 20-6 for a summary of current evidence to support interventions for patients with dyskinesias with a more comprehensive table available online.