After a stroke or spinal cord injury (SCI), there exists an inherent individual capacity for recovery of function that depends on factors such as location and severity of central nervous system (CNS) damage. This capacity can be determined early after the incident by clinical, electrophysiological, and imaging examinations. These measures can also be used as prognostic factors and, consequently, for an early selection of appropriate rehabilitation procedures. Recovery of function after a stroke mainly depends on the tract damaged and the amount of damage, e.g., recovery of hand/finger function is particularly poor after extensive lesioning of the corticospinal tract. In cervical SCI, the combination of peripheral and central nervous system damage limits recovery. As the recovery of function usually remains incomplete, an integral part of rehabilitation should be directed to compensate for the remaining motor deficit by customized assistive devices that promote independence in daily life activities. The capacity for the recovery of function can be exploited by a repetitive execution of functional movements, physically supported as far as required. This approach encourages participation by the patient and promotes appropriate proprioceptive input from limb muscles, tendons, skin, and joints under physiological movement conditions. The consequence of this knowledge is that robotic assistance has to be adapted to the actual condition and requirements of the individual patient. Furthermore, intensive training (i.e., a high number of movement repetitions and long training duration) can lead to an additional gain in function compared to low-dose conventional training. However, this gain is small compared to the spontaneous recovery of function and is often transient, due to the fact that patients will not regularly use these functions in daily life, thereby maintaining them. Finally, other promising adjuvant approaches could contribute to improving motor function in the future, such as epidural or deep brain stimulation as well as CNS repair. However, they are still in an early clinical or in a translational stage.