People with multiple sclerosis (MS) often have poor postural control, which likely underlies their increased risk of falls. Based on several studies of balance and gait in MS, it appears that the primary mechanisms underlying the observed changes are slowed somatosensory conduction and impaired central integration. This review of the published research on balance, gait, and falls in people with MS demonstrates that people with MS have balance impairments characterized by increased sway in quiet stance, delayed responses to postural perturbations, and a reduced ability to move toward their limits of stability. These impairments are likely causes of falls in people with MS and are consistent with the reduced gait speed, as well as decreased stride length, cadence, and joint movement, observed in most studies of gait in MS. Based on these findings, we identify several factors that may be amenable to intervention to prevent falls in people with MS.