The objectives of the project are to develop an upper extremity orthosis that acts as an assistive device and a therapeutic tool. This will be done by using an existing prototype called the WREX - which was developed at the A.I. duPont Hospital for Children- and redesign it for clinical use. The new WREX will come in two versions: a passive exoskeletal orthosis that is powered by elastic bands; and an active version that augments the elastic bands with small electric motors. WREX is a device that can be used by people with neuromuscular weakness such as muscular dystrophy and spinal muscular atrophy, as an assistive device that aides in activities of daily living. It can also serve as an exercise/therapy device for people recovering from a stroke. Specific aims of the project are to: 1. Design and manufacture a body-powered functional arm orthosis that builds on the existing WREX(Wilmington Robotic Exoskeleton). 2. Add small motors and a controller to WREX to provide power amplification for children with profound weakness who retain residual strength and control. 3. Test the body-powered and motor-powered prototypes for feasibility with two subjects with neuromuscular disabilities