Limited data are available on the contributory and compensatory relationships between physical education and physical activity in children. Four hundred eighty-five (280 girls) children in first through sixth grades wore sealed pedometers during waking hours, including normally scheduled physical education lessons. The least, moderately, and most active children accumulated approximately 1,700, 1,100, and 2,500 more steps/day, respectively, on school days with physical education. No compensatory increases in physical activity were found on school days that did not offer physical education. The implications of the contributory relationship are highlighted by the evidence that 50% of the least active children were at risk for overweight or overweight and that no compensatory increases in physical activity were found on school days when physical education classes were not scheduled. (Contains 4 figures.)