Abstract: Apparatus and process for continuously and repetitively producing grocery sacks from a thermoplastic web at high speed, including particularly a folding operation involving applying grasping action to bag blanks formed from a heat sealed gusseted flattened tubular web of, e.g., high density polyethylene at the upper and lower portions thereof, respectively, causing said portions to be forwarded at differential longitudinal speeds whereby a rough folded bag bottom is formed. Preferably, the web is flexed as by introduction of air to the bag blank or sack to release the respective web faces and facilitate folding. A complete apparatus includes sealing, cutting, folding and pressing means and may incorporate printing and like ancillary features.