A retaining wall block has parallel top and bottom faces, a front face, a rear face, first and second side wall faces and a vertical plane of symmetry extending between the front and rear faces. The block is formed as a body portion including the front face, a head portion including the rear face and a neck portion connecting the body portion and the head portion. The body, head and neck portions each extend between the top and bottom faces and between the first and second side wall faces. An opening extends through the neck portion from the top face to the bottom face, dividing the neck portion into first and second neck wall members extending rearwardly from the body portion to the head portion.