Abstract: A mold guidance system for preventing horizontal movement of the mold of a concrete block making machine including, on each side of the machine, a mold support arm extending laterally outwardly from the inside corner of the mold and including a bushing in the outer end thereof, a first clamp secured to the side of the machine frame above the mold arm bushing, a second clamp element secured to the side of the machine frame below the mold arm bushing, and an elongate pin slidably movable within the mold arm bushing and fixedly engaged at the upper end by the first clamp and at the lower end by the second clamp. The mold guidance system prevents horizontal movement of the mold so as to reduce mold wear and increase mold life.