A modular shelving system is disclosed. In an embodiment, a box shelf is provided that may be supported by vertical rails of a shelf upright. The box shelf may be supported by shelf supports that engage the vertical rails. The box shelf may include a slideable shelf mounted on a rail and held in position by a biased hinge plate. The slideable shelf may include a divider to separate the shelf into one or more regions and to interfere with the rapid removal of products from the shelf. The box shelf may further include a door that in an embodiment may be required to be opened before products can be removed from slideable shelf.