Abstract: An alignment tool for use by a shingle installer for aligning a row of shingles to be fastened to a roof, the shingles having straight bottom edges relative to a previously fastened row of shingles. The alignment tool includes a pair of flanged brackets that fit snugly against the lower edge of the already fastened shingles and includes an upper edge that allows the shingles to be fastened to be quickly placed thereagainst for proper alignment. The installer can kneel, holding the alignment tool in position while actually fastening the shingles to the roof with his free hands.