Hemiparesis of the upper limb is one of the most serious and most common impairments resulting from stroke. Approximately 75% of the over 750,000 strokes that occur annually in the United States cause some degree of upper extremity paralysis. Approximately 65% of stroke survivors still cannot use their affected hand to assist with activities of daily living 6 months after their stroke. The impact of upper extremity impairments on disability and health is great, yet there are relatively few rehabilitation interventions designed to restore function to the impaired upper limb. Therefore, our long-term objective is to develop upper extremity rehabilitation therapies that are effective at restoring arm and hand function, that are applicable across a wide range of impairment severity, and that are readily implemented in the present healthcare environment. The purpose of this study is to estimate the efficacy of Contralataterally Controlled Functional Electrical Stimulation (CCFES) in reducing upper extremity impairment and activity limitation in chronic upper extremity hemiplegia. CCFES is a rehabilitation intervention in which neuromuscular electrical stimulation (NMES) is applied to the finger and thumb extensor muscles of the paretic upper limb to open the hand. The stroke survivor controls the stimulation intensity, and consequent degree of hand opening, by modulating the degree of opening of the contralateral unimpaired hand, which is detected by an instrumented glove. Thus, volitional opening of the unaffected hand produces stimulated opening of the affected hand. The stimulation paradigm is used to assist the stroke survivor in practicing functional tasks with their affected hand. Pilot studies of CCFES in chronic hemiplegia were encouraging. This project will expand on the work already begun by: 1) determining if 12 weeks of CCFES is therapeutically effective in chronic stroke survivors, 2) determining if a plateau in treatment effect is achieved before 12 weeks is completed, 3) determining how initial level of motor impairment affects treatment efficacy, and 4) determining whether therapeutic gains persist over time. We will conduct a randomized controlled trial in which 102 chronic stroke survivors (>6 months post-stroke) will be randomly assigned to receive 12 weeks of CCFES or cyclic NMES, an intervention that provides electrical stimulation of the hand extensors, but with preprogrammed timing and intensity. Randomization will be stratified on two levels of baseline hand impairment defined by the degree of voluntary finger extension present. Assessments of upper extremity impairment and activity limitation will be made every 3 weeks during the treatment period and every 2 months during a 6-month follow-up period. This study is the first randomized controlled trial of CCFES in chronic upper extremity hemiplegia. Ultimately, the information learned in this study will serve to accelerate the development of treatments for reducing post-stroke disability.