Abstract: A carton divider comprising a structural web surrounding a plurality of preformed cateval flaps each circumscribed in part by an edge broken away from the web along a readily frangible line of weakness extending from one end to another end of a laterally extending hinge line arranged on the web. The plurality is arranged as laterally extending flap pairs, each pair comprising a laterally elongated first flap in laterally spaced relation across an intermediate isthmus of the web, from a laterally shorter second flap. A longitudinal array of such pairs have adjacent pairs with a mutually laterally reversed symmetry with laterally offset isthmuses arranged in a contiguous series forming a serpentine spine running along a central longitudinal axis of the web. The elongated flaps are arranged with proximal edges thereof adjacent the central axis in spaced relation from the axis sufficient to admit a divider insert to be positioned in upright supported relation by and between the proximal edges.