Abstract: An adjustable guide assembly for use by a stone mason in constructing a brick wall so that the bricks thereof are uniformly spaced forwardly from a preexisting subwall. The guide assembly includes an elongated guide member having a longitudinally extending substantially straight guide face thereon, an elongated spacer element and a clamp for securing the spacer element to the guide member so that it extends outwardly from the guide face by a predetermined gauge distance. After an initial or bottom row of bricks has been laid so that the front surfaces of the bricks therein are spaced forwardly from a subwall by the gauge distance, the guide assembly can be utilized by positioning it so that the guide member is in a substantially vertical disposition with the guide face in engagement with the front surfaces of the bricks in the bottom row and so that the terminal end of the spacer element is in engagement with subwall.