A mold and method for making a hollow core concrete block. The mold has two opposing side walls; a bottom wall; a front wall; a top side with an opening through which the block can be removed from the mold; a cover, and a rear side through which liquid, such as concrete, can be poured into the mold. Extending from the two side walls are a pair of trunnions about which the mold is rotatable, such that when the mold is suspended by the trunnions and the mold is empty, gravity rotates the mold from a block-removal orientation in which the top side faces upwards to a mold-filling orientation in which the rear side faces upwards. The trunnions are also positioned such that when the mold is filled with the liquid, gravity rotates the mold from the mold-filling orientation to the block-removal orientation.