Abstract: A planar leveling device includes first and second elongated, substantially rigid support members. Each member is more than about a foot in length. The first and second support members define the plane of the device and have a uniform, equal maximum heights in directions perpendicular to the plane. The members also define the maximum height of the device in those directions. Each of the two support members provides a thin edge along a planar side of the device to provide full, continuous support yet minimize the contact between the device and adjoining masonry elements. Reinforcement members may be provided on one or both sides of the support members, in the plane of the device, for greater strength and versatility. Substantially solid, unbroken sides of the support members permit the compression of mortar into the joint formed by the device between parallel adjoining courses of masonry elements in a wall.