Abstract: The present invention is directed to a system and method for laying masonry blocks in multiple block units. The system comprises a mortar injection device, a block hoist apparatus and a mortar applying apparatus, The mortar injection device includes a mortar feed, mortar dispensing chutes and a block tamper. The mortar dispensing chutes are positioned to inject mortar into gaps between adjacent blocks in the multiple block unit, to create a mortar joint between each block. The block tamper comprises a vibratory roller and/or a series of vibrating pistons attached to the mortar injection device, and facilitates substantially uniform settling of the mortar in the block gaps.