The backing for the dust mop has a relatively long pocket extending from one end of the dust mop for a substantial portion of the length thereof, terminating a short distance from the other end and being open at such other end for insertion of a slip-through frame therein. Extending from the other end of the backing is a much shorter end pocket having an open inner end which overlies the open inner end of the longer pocket. This has the advantage that when the slip-through frame is fully received within the backing and the shorter pocket is pulled over the adjacent end of the frame and into overlying relation with the open end of the larger pocket, the frame cannot very easily slip out of the backing by mistake.