Most existing exoskeletons have followed a similar design approach using articulated rigid links, despite the applications of strength augmentation or rehabilitation, which may have very different specifications. In order to address the urge for ergonomics in wearable assistive exoskeletons for rehabilitation, this paper proposed a design alternative using compliant continuum mechanisms. Design concepts were elaborated for an upper extremity exoskeleton for a shoulder joint. Design considerations were then detailed based on a general kinematics and statics model extended from previously published results. Construction, actuation and transmission schemes for a selected continuum structure were discussed and a preliminary prototype was constructed to demonstrate feasibility of the proposed idea.