Abstract: A tool for temporarily holding one or both ends of a piece of wallboard or plaster-board adjacent a ceiling joist to assist in nailing or otherwise fastening the board to the joist is disclosed. In one embodiment the tool includes a right angle plate with a handle at the bottom and an inverted U-shaped flange along the top edge for engagement over a joist as the end edge of the wallboard is carried and supported by the plate. The U-shaped flange is dimensioned from the plate so as to be engageable of joists of different widths. In another embodiment the inverted U-shaped flange is adjustable so that different widths of joists can be accommodated to bring the end edge of the wallboard relatively close to the bottom edge of the joist for convenience in nailing.