Abstract: A shelf structure comprises a plurality of interconnected posts and shelves. Spaced apart annular recesses or ribs are provided on the posts for positive engagement with corresponding ribs or recesses respectively formed on the insides of multi-piece collars which are placed in position about the posts. A fastening ring either slips over the collar or is screwed upwardly onto the collar to lock it into position and to provide an upwardly facing shelf-supporting surface. Shelf-clamping rings are then screwed downwardly on the collars to abut the top surfaces of the shelves.