Our military forces are experiencing an increase in injury to the upper extremity from combat and strains of overuse resulting in pathologies such as tendonitis, bursitis, and impingement. Rehabilitation using robotics offers significant advantages over manual therapy such as accuracy and consistency of applied forces, quantitative measures of performance, and lack of therapist fatigue. This project will implement common shoulder therapy protocols on a robotic arm exoskeleton and conduct a pilot study to evaluate operational use. The goals of this project are to 1 transfer common shoulder therapy protocols to the exoskeleton 2 design, code, and test the exoskeleton control system 3 conduct a pilot study to validate operation on a range of subjects. Protocols will be developed based on biomechanical analyses of tasks being performed using conventional shoulder therapy protocols. Control algorithms will be used to produce resistance therapy about the shoulder axes as well as generate functional movement patterns of the arm. The distributed software design will incorporate a NASA fail-safe architecture that continually monitors potentially hazardous conditions to ensure patient safety. Through the focused development effort proposed here, the Maryland-Georgetown-Army MGA Exoskeleton has the potential to become a highly effective tool in treatment facilities ranging from military rehabilitation centers to sports therapy clinics.