Abstract: A machine for erecting flat box blanks and for closing one end of the erected box comprises a feed guide dimensioned to receive a stack of flat-folded blanks, and a forming slot at an end of the feed guide, the forming slot being dimensioned to receive an erected box but consequently too small to accept a flat-folded blank. A suction head carried by a drive jack is effective to pull a box blank from the feed guide into the forming slot, with simultaneous erection of the blank to form the rectangular box, and immediately after that two folding blades converge on the box to fold-in side flaps ready for folding down an end flap of the box. The folding of the end flap is accomplished by a closing fork operating in a direction perpendicular to the plane of action of the closing blades and effective to fold over both an end panel, and a terminal tab which tucks into the box to ensure closing.