A combination screw and clearance drill (10) is provided that in one mode of operation is able to drill a pilot hole for the screw threads (15) through a top piece of material and then screw into a lower piece of material, thus enabling the two pieces of material to be screwed tightly together in a single operation. The screw is designed in such a manner that the ability of the screw to drill a clearance hole for the threads does not substantially effect the gripping ability of the screw. In one direction of rotation by use of a reverse helical drill flute (18) recessed in the shaft, the screw is able to drill the clearance hole for the threads of the screw and by reversing the rotation the screw is able to stop drilling a clearance hole and function as a regular screw. Flutes (24) in the screw head cut a counter bore for the head when the head contacts the surface of the top piece of material.