Gait speed is a significant predictor of future disability, cognitive decline, falls, hospitalization, nursing home admission, and mortality. As a strong indicator of such outcomes, gait speed has been referred to as an important vital sign in older adults. Although gait speed is quick and easy to measure, testing protocols can vary greatly on the basis of starting procedure (standing vs dynamic), distance covered, and pace of the walk (usual vs fast), all of which can impact the gait speed recorded. Gait speed has established reliability and validity, and measures of meaningful change range from 0.04 to 1.2 m/s. Average gait speeds for community-dwelling older adults range from 0.60 to 1.45 m/s with a desired gait speed often cited as 1.2 m/s, the speed required to cross most intersections. In summary, gait speed requires little time, effort, or equipment to measure, and provides information useful in clinical recognition of dysfunction, making a prognosis and monitoring for change in status.