Abstract: A free-standing shelving system of the type comprising four uprights supports a plurality of rectangular shelves. Attachment of the shelves at each corner is to one of the uprights. Each shelf 5 is formed at each corner with a corner piece 12 which is shaped to define protruding bridge pieces 15, 16. An upright 4 is of generally W-section having a re-entrant portion formed by surfaces 21, 22 in which are formed holes 11 which are shaped and mutually spaced so as to receive the bridge pieces 15, 16. When the shelf is in place, the bridge pieces 15, 16 extend through to the exterior of the re-entrant portion, and this allows a peg 24 to be dropped into the longitudinal passageway thus defined to thereby firmly lock the assembly together.