Abstract: A leveling assembly to establish elevations in a building structure for installing cabinets, bookshelves, countertops, etc. There is a telescoping mounting post adapted to be positioned in bearing engagement between a floor surface and the top of a doorway, ceiling or other upper surface. A laser that transmits a horizontal laser beam is mounted to a mounting device that can be moved to different positions along the length of the post. Locking devices hold the laser mounting device in place, and also properly position the post to be in firm engagement with its bearing surfaces. The laser mounting device can be swung to upper and lower positions.