A siding application tool and a method for installing siding using the tool is described. The tool includes an overlap portion having upper and lower ends, an L-shaped hook portion with an upper bearing surface that forms a generally right-angle hook with the overlap portion, an L-shaped retainer portion with a lower bearing surface that forms a generally right-angle retainer with the overlap portion, and a plate member which may optionally include a slot configured to accept the tongue of a tape measure.