This article presents an overview of dynamic biomechanics of the asymptomatic foot and ankle that occur during walking and running. Functional descriptions for walking are provided along with a review of quantitative findings from biomechanical analyses. Foot and ankle kinematics and kinetics during running are then presented, starting with a general description that is followed by more specific current research information. An understanding of the dynamic characteristics of the symptom-free foot and ankle during the most common forms of upright locomotion provides the necessary basis for objective evaluation of movement dysfunction.