The prosthetic rehabilitation of upper limb amputees presenting a high-level amputation is a very challenging target due to the severe disability of the patients and to the current lack of commercial prosthetic solutions adequate to significantly restore a sufficient quality of life. Two contrasting aspects are extremely important to satisfy the patients' requirements, i.e. the Functionality and the Wearability of the prosthesis. This book presents the activity that was performed for the development of a novel powered shoulder articulation and its introduction in a current myoelectric prosthesis. The approach followed for the design process has been formalized in a procedure that makes it possible to tackle the problem of prosthetic rehabilitation from a general perspective, consistently combining clinical aspects and technical issues. The application of the procedure determined the design guidelines of the new device, which was finally designed, prototyped and tested. The book is mainly addressed to the community working in the specific field of Upper Limb Prosthetics and/or the field of Upper Limb Robotic Rehabilitation, since many key issues are common to both the disciplines.