Abstract: An adapter releasably attaches to an existing wall-mounted shelf standard to provide a desired slot configuration for new shelf supports. The adapter includes a body portion having a fixed, rearwardly extending jaw member and further includes a movable rearwardly extending jaw member mounted on a threaded post which extends through the body portion. The jaws are received into the slots of an existing shelf standard and the post is rotatable to draw the movable jaw toward the fixed jaw to grasp the front wall of the shelf standard. The body portion includes a slotted front surface facing having the desired slot configuration for receiving the mounting tabs of a new shelf support.