A litter box includes a tray having a bottom wall and side walls extending upward from the bottom wall. At least one of the side walls has an upper portion that is moveable from a retracted position to an upright position. A plurality of bags are in the tray, each containing a layer of litter. The layers of litter are separated from one another by the bags. In another embodiment, the plurality of bags of litter are provided in an outer bag that can be placed into a tray. In use, upper portions of each bag are lifted over the side walls to expose the litter in that bag. After use, the entire layer of litter can be removed by removing the associated bag. The next layer of litter is then exposed for use.
