There have been well-documented increases in overweight and obese children, sedentary lifestyles, and increased prevalence of a hypokinetic disease over the past 20 years. Thus understanding the physical activity patterns of children is essential for developing effective interventions. Little evidence exists that illustrates the contribution of weekend, physical education, and non-physical education days to overall physical activity patterns of children. The purpose of the study was to examine differences in pedometer-determined physical activity patterns of fourth and fifth grade children during weekend, physical education and non-physical education days. Three hundred and sixty-three children (8-11 years old) from six Southwestern USA elementary schools participated by wearing pedometers (Yamax Digiwalker SW-200) for seven consecutive days. Children recorded their steps at arrival to school and when they woke up and went to bed on weekend days. During weekdays, the fourth and fifth grade children averaged 13,196 ± 3,334 and 11,295 ± 3,168 steps/day for boys and girls, respectively. This is compared to a weekend average of 7,660 ± 4,647steps/day (boys) and 7,317 ± 4,062 steps/day (girls). Children were significantly more active on physical education days, averaging 12,979 steps/day (14,197 ± 4,697 steps/day for boys and 12,058 ± 3,772 steps/day for girls),compared to non-physical education school days, when they accumulated 11,809 steps/day (12,788 ± 3,600 steps/day for boys and 11,047 ± 3,382 steps/day for girls). Based on the findings in this study, children and youth are more active during school days than on weekend days. Furthermore, children are more active on physical education days than non-physical education days. These findings suggest that increased physical activity programming and interventions during weekend days may be needed to increase physical activity. The expansion of school-based physical education across more school days may also serve to increase children's physical activity during the school week.