A mechanism for automatically forming and laminating flaps of individual carton blanks as the blanks are moved along a prescribed longitudinal path. The mechanism includes a hopper for supplying individual carton blanks to a conveyor that leads along the prescribed path away from the hopper. A vacuum head is movably located below the hopper to remove successive blanks therefrom. The suction head moves the individual blanks downwardly into engagement with the conveyor. Lugs on the conveyor move the successive carton blanks along the path toward a flap folding mechanism. The flaps are folded over onto the carton blank in two separate steps. Firstly, the flaps are folded upwardly to a substantially 90 degree orientation with the remainder of the blank. This is done by a pair of pivoted arms on opposite sides of the conveyor. As the carton blank continues to move along the conveyor, the upwardly folded flaps are engaged and folded on downwardly into engagement with the remainder of the blank. Pressure rollers are provided at a discharge end of the conveyor to firmly press the folded flaps against the blank bodies. The rollers are driven at a speed greater than the operational speed of the conveyor so as to pull the blanks from engagement with the conveyor lugs and direct them to a carton forming station. The complete flap laminating operation is performed as the cartons move along the path toward a carton forming station.