The development of coordination of leg movements of human infants is discussed from the perspective of dynamic motor theory. Even in the newborn period, leg movements have topographical and temporal organization, but it is global and inflexible. During the first year, limb segments become both disassociated from these global synergies and reintegrated into more complex coalitions. Growth-related changes in the biodynamic properties of the body segments may be as important as neurological maturation in determining the movement outcomes and may help explain the spurts, regressions, and asymmetries seen in early infancy.