An interior rearview mirror assembly includes a mirror head and a mounting assembly for adjustably mounting the mirror head at an interior portion of a vehicle. The mounting assembly includes a mounting structure that is attachable to an interior portion of the vehicle and includes a mirror mounting element pivotally attached at an end of the mounting structure to establish a mirror ball pivot joint. The attaching portion of the mirror mounting element is configured to attach to a receiving portion of the mirror head via a snap connection and/or a twist connection. The attaching portion of the mirror mounting element, when the mirror mounting element is attached at the end of the mounting structure, is attachable to the receiving portion of the mirror head from a position rearward of the mirror casing and from exterior the mirror casing to attach the mirror head at the mounting structure.