Weight support can facilitate upper-limb movements, with which the patients may do more and more meaningful exercises earlier in the rehabilitation process. Most rehabilitation devices support the arm against gravity in one way or the other. Weight support can be realized by limiting vertical displacement or applying constant supportive forces which counteract the gravitational pull. Of these, using constant supportive forces is the most natural way to facilitate natural arm movements as it allows full freedom of movement and the amount of weight support is scalable to the patients needs. To apply the supporting forces to the arm, endpoint mechanisms and exoskeletons are more complex to build and use then cable suspensions, but offer more control over the movements. Finally, passive weight support is inherently safe, but active systems have enhanced control options and the capability to create training conditions beyond limb weight.