Disclosed herein is a sign support collapsible for transport and which is conveniently adjustable to accommodate signs of various dimensions. The sign support comprises an assembly of an L-shaped upright provided with a pointed spike at one end and with a cantelevered foot extension by which the uprights may be driven into ground. Formed in one surface of the L-shaped uprights are a plurality of elongate, longitudinally aligned and longitudinally spaced slots each dimensioned to receive an offset clasp extending from the back side of a U-shaped lower sign channel. An upper sign channel, similarly U-shaped in section, is provided with an L-shaped clamp on the back side thereof terminating at the free end in a split circular hoop which, at the juncture of the split, extends in an opposing tab for grasping one of the surfaces of the L-shaped upright. In this manner the upper channel can be conveniently mounted by rotating the L-shaped clamp onto one surface thereof, allowing for height adjustment and furthermore providing in the hoop opening a pocket for receipt of flag poles or other advertising structures.