This issue of Physical Medicine and Rehabilitation Clinics, guest edited by Dr. Miriam Segal, will cover the important topic of Muscle Overactivity in Upper Motor Neuron Syndrome, including assessment and problem-solving for complex cases. Topics discussed in the volume will include: Functional/problem based assessment in patients with spinal cord injury; Special considerations in pediatric assessment; Special considerations and assessment of spasticity and multiple sclerosis; Pharmacologic treatment tools; Peripheral neurolysis; The role of physical and occupational therapy; Neurosurgical approaches; The neuro-orthopedic approach; Upper extremity problem-solving: Challenging cases; Lower extremity problem-solving: Challenging cases; and Emerging therapies.