Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS) and the most widespread nontraumatic cause of disability in young adults around the world. MS occurs in people of all ages, races, and ethnicities. MS is characterized by clinical symptoms resulting from lesions in the brain, spinal cord, or optic nerves that can affect balance, gait, and fall risk. Lesions accumulate over time and occur in different areas of the CNS causing symptoms that include weakness, spasticity, and fatigue, as well as changes in sensation, coordination, vision, cognition, and bladder function. Thus, it is not surprising that imbalance, gait dysfunction, and falls are common in people with MS. The overwhelming majority have abnormalities of postural control and gait even early in the disease course. In all, 50–80% have balance and gait dysfunction and over 50% fall at least once each year. Balance dysfunction in MS is conceptualized as three interrelated problems: decreased ability to maintain position, limited and slowed movement towards limits of stability, and delayed responses to postural displacements and perturbations. In addition, functional balance performance may be affected by impaired dual-task integration. Walking changes in MS include reduced gait speed, impaired walking balance, and reduced walking-related physical activity. Falls in people with MS are associated with injuries, reduced participation, and increased fear of falling. A wide and growing range of rehabilitation and medical interventions are available to address the changes in balance, gait, and fall risk associated with MS.