Worldwide, 92% to 94% of schoolchildren carry backpacks1,2 and frequently complain of shoulder and back pain.1,3 On average, children load their backpacks between 10% to 22% body weight (BW).4,5 An understanding of how loads are distributed under backpack straps may help identify the source of shoulder and back pain in children. The purpose of this study was to quantify the contact pressures and perceived pain under backpack straps while children carried varying loads.