Disclosed are embodiments of an edge registration system and method. The embodiments employ a compiling tray with a fixed side edge. A movable backstop stops each sheet as it is fed into the tray. A tamper tamps each sheet against the fixed side edge. The registered stack is then aligned with one or more finishing mechanisms by a repositioner that laterally repositions the stack and by the movable backstop that repositions the stack between the front and back ends of the tray. Because the fixed side edge covers the entire paper length and because the paper is only tamped a short distance to achieve registration, the system provides greater support for squaring the sheets. Additionally, because the paper is only tamped a short distance to achieve registration and because the backstop is only moved during alignment of the stack with a finishing mechanism, the system is capable of improving productivity.