Abstract: The disclosure relates to a three cell divider for a rectangular corrugated box which may be fabricated from a single sheet of corrugated board by cutting and scoring operations thereon, and then erected for insertion in the box. The divider comprises a horizontal bottom portion having two panel portions integrally secured to opposite sides and opposite ends of the bottom portion and respectively foldable into an upright, horizontally U-shaped configuration, thus defining two divider walls and four walls abutting the box walls. Projecting tabs on the free ends of two of the abutting walls engage notches in opposed corners of the horizontal bottom portion to maintain the divider in its erected position.