A shelf support system includes a sleeve or wedge member and a collar adapted to be secured to a generally cylindrical support post, that is one that is circular when viewed in radial cross-section. The sleeve has an inner surface that is configured to embrace the support post and an outer surface formed with a first axially outwardly inclined wedge portion and at least one second axially outwardly inclined wedge portion that, when viewed in such radial cross-section, extends at an angle to the first portion. Additionally, the collar is adapted to be secured to a member to be supported and to embrace the sleeve. The collar has a first wedge surface formed to mate with the first portion of the outer surface of the sleeve and at least one second wedge surface formed to mate with the second portion of the outer surface of the sleeve. Thus, when the sleeve embraces the post and the collar embraces the sleeve, axial loading of the collar in one direction causes the first wedge surface to mate with the first portion of the outer surface of the sleeve and the second wedge surface to mate with the second portion of the outer surface of the sleeve, thereby urging the sleeve toward the post in at least two generally radial directions.