Abstract: An apparatus is disclosed for screening and separating wood chips or the like according to thickness. In the illustrated embodiment, the apparatus comprises two generally horizontal decks mounted one beneath the other, and with each deck having three screening sections disposed in a serial arrangement along its longitudinal length. Each screening section comprises an opening in the associated deck, a stationary grid composed of parallel rod elements disposed in the opening, and a movable grid which is also composed of a plurality of rod elements and which are disposed in alternating relation with the rod elements of the stationary grid. Further, the grids are arranged so that the gaps between the rod elements are parallel and of predetermined uniform separation throughout.