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. The block hoist apparatus includes a mechanical hoist, a hoist transmission member, a weight distribution beam, gripping arms pivotally attached to the weight distribution beam, major gripping members associated with each gripping arm and mounted on a gripper mounting bar, at least one minor gripping member also mounted on the gripper mounting bar and digitally spaced from a corresponding major gripping member. At least a portion of each of the major and minor gripping members are insertable into different blocks of a multiple block unit and cooperate, upon lifting of the weight distribution beam by the mechanical hoist, to exert a clamping force along an interior portion of the blocks to retain the blocks in alignment for raising and lowering of the multiple block unit. The mortar applying device includes a mortar applicator, a housing for the mortar applicator, a housing guide and means for controlling the dispensing of mortar onto the top surface of a row of blocks, while substantially limiting application of mortar into the inner cavities of the blocks.