To determine the normal gait patterns in childhood, gait studies were performed on 186 normal children between the ages of one and seven years. Rotations of the lower-extremity joints in the sagittal, frontal, and transverse planes; step length; cadence; walking velocity; and duration of single-limb stance (as percentage of the gait cycle) were analyzed throughout a walking cycle using high-speed movies, a Graf-Pen sonic digitizer, a computer, and a plotter as well as electromyograms. The sagittal-plane angular rotations in children from two years on are very similar to those of normal adults. Subjects less than two years old have greater knee flexion and more ankle dorsiflexion during stance phase, and their knee-flexion wave (stance-phase knee flexion after foot-strike and subsequent knee extension prior to toe-off) is diminished. Also, external rotation of the hip in these younger subjects is pronounced. Reciprocal arm-swing and heel-strike are present in most children by the age of eighteen months. Since these commonly accepted indicators of gait maturity are present very early, we measured other gait determinants and found that the five important determina4ts of a mature gait are duration of single-limb stance, walking velocity, cadence, step length, and the ratio of pelvic span to ankle spread. As maturity advances, cadence decreases while walking velocity and step length increase. Importan! factors in the development of a mature pattern of these determinants are increasing limb length and greater limb stability, manifested by the increasing duration of single-limb stance (an index of limb stability). A mature gait pattern as determined by these criteria is well established at the age of three years.