Apparatus is disclosed for preparing side-stitched documents. The apparatus includes means for feeding a series of sheets to be included in said document in a paused, timed, preselected order, a downstream, in-line accumulating station to receive the sheets, first clamping means associated with the accumulating station for grasping a complete assembly of sheets on the side opposite the side to be stitched, and means for moving said clamped assembly to a downstream, in-line stitching station. The stitching station includes a stitching head to make two or more stitches in the assembled sheets at selected loci along their edge, means for moving the stitched assembly downstream from the stitching station, stop means downstream of the stitching station to stop movement of the side-stitched document, second clamping means associated with said stop means for grasping the document on its upstream side transverse to the stitched side, means for releasing the first clamping means from the document and returning said clamping means to the accumulating station, and means for releasing the second clamping means and transferring the side-stitched, document to a packing station.