Abstract: A backpack with integral frame formed of plastic sheets without metal supports. A load carrying sack having a front face, a pair of shoulder straps and a waistband, and a support pad mounted on the front face, the pad comprising a foam sheet of a first height, a stiffener sheet of a second height less than said first height, and a protective sheet, with the three sheets attached to the front face by stitching forming vertical panels and upper and lower horizontally pivoting structures with a stiff intermediate structure.