A wall construction system includes a plurality of leveling blocks arranged in a first course wherein each leveling block including an upper surface, a wall defining a leveling block void, and at least one leveling component having a leveling plate that engages the wall and at least one threaded adjuster extending through the plate. A plurality of field blocks is arranged in a second course atop the first course wherein each field block includes a lower surface that interfits with the upper surface of at least one of the leveling blocks and a wall defining a field block void aligned with the leveling block void of the one leveling block. A cementitious material is disposed in an aligned field block void and leveling block void of at least one of the field blocks and at least one of the leveling blocks, respectively.