Traumatic brain injury (TBI) impacts the lives of 1.5 to 2 million new individuals each year; 75,000 to 100,000 of these are classified as severe, and will suffer enduring severe spasticity in addition to cognitive, vestibulomotor (balance), and other motor impairments. Following TBI, the onset of spasticity and associated orthopedic sequellae is rapid, beginning as early as one week following injury. The progressively developing spasticity and other disabilities often represent the most significant barriers for practical re-entry of TBI patients into the community. The lack of sufficient data regarding the neurobiology of TBI-induced spasticity and safety, feasibility and efficacy of early intervention therapy direct the current treatment guidelines to a conservative level. This chapter focuses on several quantitative physiological measures of spasticity, some recent findings regarding a neurobiological basis of spasticity, and finally, a section describing present treatments and the experimental treatments and rehabilitation of TBI-induced spasticity.