Abstract: Apparatus for forming a hinged or clamshell type carton from a paperboard blank includes a carton forming die for receiving the paperboard blank, a movable frame for transferring the carton blank from the stack into registration over the die, and a reciprocating plunger mounted above the die for forming the carton. The blank is formed into a finished carton in one simple harmonic motion. The movable frame includes a number of vacuum assisted suction cups for lifting the carton blank from the stack and at least a pair of gathering rollers which cooperate with a pair of pivoting blades mounted adjacent the die to fold and gather the hinge of the carton blank as the blank is positioned and pressed into contact with the die. A pair of inverted "T" retaining bars, disposed on the die adjacent the carton hinge, prebreak glue tabs on the carton and capture and retain the wall panels of the carton when the blank is pressed into registration with the forming die.