To be able to independently perform daily activities, it is important that humans can use their arms and hands to a sufficient extent. The positioning of the arm and the execution of grasping tasks play an essential role in this. Disability caused by impairments of arm and hand function can lead to activity limitations and participation restrictions. Assistive devices can contribute to reducing the effect of disability. However, these devices must meet users’ expectations regarding effectiveness, reliability, durability, comfort and ease of use to reduce the risk of device abandonment. In this thesis we developed and evaluated three novel assistive devices that support patients with impaired shoulders or hands. During the design process we focused on restoring performance (i.e. on the activity and participation level) rather than restoring capacity (i.e. on the impairment level).