A shipping box (11), shipping box and pallet assembly (10), and a blank (B.sub.1, B.sub.2, B.sub.3) for making the shipping box. The box has integral attaching tabs (38) projecting downwardly therefrom, with at least one slot (31, 32) therein for receiving an extended end (41) of at least one slat (40) on a pallet (13), to releasably attach the box to the pallet. A reinforcing insert (70) is placed in the box against opposite walls. The insert has a center panel (77) of the same width and height as the box wall against which it is placed, and double thickness end panels (78) at opposite sides of the center panel, extending perpendicular to the center panel and lying against adjacent box walls.