Abstract: Method and apparatus for erecting carton blanks having preformed fold lines in which flat carton blanks are pressed into a pair of hollow forming shafts by a plunger assembly of complementary configuration to form hingedly connected lid and tray portions.The plunger assembly comprises a pair of movable plunger members which undergo synchronized translational and rotational movement and in cooperation with a swingable plate to erect hingedly connected sidewalls of the tray and lid portions. When the side panels of the lid and tray portions of the carton are erected, they are held by the plunger assembly against stationary bottom portions of the shafts. Finger assemblies undergo rotational and reciprocating motion to fold glue bearing edge flaps of the lid and tray portion into their assembled position to maintain associated side panels in their erected position to enable the glued portions to "set". A novel carton blank which is provided with "biasing tabs" is also described.