We observed the gait patterns, including time and distance measurements and ground reaction forces, of fifty-one normal children. Thirty-three children were retested once at one, three, six, nine, or twelve months, over a two-year period, for a total of eighty-four gait observations. Time and distance measurements and foot-ground reaction force measurements were found to be dependent on walking speed and the age of the child. An increase in height with age was found to be the major factor in determining the changes in time and distance measurements with age. For example, we found that average stride length was 76 per cent of the child's height at a walking speed of 1.04 meters per second regardless of the child's age. In contrast, the three components of foot-ground reaction force (vertical, lateral, and forward directions) were observed to vary with age up to five years even when normalized. After the age of five years an adult pattern of ground reaction force emerged. In addition, we found that walking patterns of children who were more than found years old did not vary when retested within a three-month period. However, for children less than four years old, measurements were found to change due to growth during the three-month period to retesting. Similar changes due to growth were found in children more than four years old who were tested at intervals more than three months apart. This important finding may be clinically useful in the study of the effects of treatment.