An interior rearview mirror assembly for a vehicle includes a reflective element and a casing. An attachment plate is secured to the reflective element and an electronic circuitry element, such as a printed circuit board, is attached to the attachment plate. The attachment plate includes at least one mounting member protruding through the circuit board for engaging a mounting assembly that mounts the mirror assembly to an interior portion of the vehicle and directly supports the attachment plate, along with the printed circuit board and the reflective element at an end of the mounting assembly. The mounting assembly may comprise a toggle assembly for a prismatic reflective element.