Abstract: Apparatus for stacking fan-folded paper including an oscillating chute through which paper received by the stacker from a printer passes toward a pedestal on which the paper is to be stacked. The stacker receives line strobe signals from the printer indicative of the rate at which paper is fed by the printer to the stacker. The line strobe signals control the rate of oscillation of the chute between two extreme positions. The distance between the two positions defines the oscillation stroke which is determined by means of a manually-operable selector to be a function of the form length of the paper to be stacked. The paper is stacked on a pedestal which is incrementally movable between top and bottom positions. A stack sensor is provided which senses the top of the stack and causes the pedestal to move toward the bottom position so as to maintain the distance between the chute and the top of the stack relatively constant.