Abstract: Apparatus for the head-to-tail stacking of objects or groups of objects, such as folded cardboard packaging boxes, which are substantially identical in terms of their shapes, their dimensions and the orientation with which they are presented to the apparatus. The apparatus includes an aligning and retaining device which is mounted on a shaft extending above and transversely with respect to a conveyor. The aligning and retaining device is arranged to remove and invert a first batch of objects at the same time as abutments position a second batch below the first batch. The first batch are then laid on the second batch to form a stack.