Abstract: A self-aligning construction block consisting of a basic double block having two flat vertical sides connected by two flat vertical end surfaces, the sides being twice the length of the ends with compound angled top and bottom surfaces having two hollowed center portions for receiving a reinforcing cement fill. The top and bottom surfaces of the basic blocks complement each other for automatic stacking. In construction of a wall, the top surface of modified top blocks and the bottom surfaces of modified bottom blocks are flat and at right angles to the side and end surfaces. The angular relationships of the basic block's top and bottom surfaces perforated by two hollow wells allow for reinforcement rods to lie in a transverse axis and at right angles thereto across each hollow well in a substantially coplanar relationship. Any odd space at the end of a wall is taken up by a half block which is constructed exactly as one half of the basic double block.