A label holder or label/sign holder to be secured to a merchandise-supporting shelf devoid of a C-channel on its depending front lip. An adaptor element is secured to the supporting surface of the shelf as by push pins and has a forwardly extending portion defining a hook member engageable in a lip member defined at the upper edge of the body panel of the label holder without interfering with movement of a transparent cover member on the label holder to insert or remove labels from a pocket defined therebetween. Various embodiments of rearwardly extending flanges on the back of the body panel are adapted to secure the lower portions of the label holder to or around a rearwardly extending flange on the bottom of the shelf lip.