An inside rearview mirror assembly for vehicles preferably including four parts, namely, a molded breakaway mirror support bracket, a molded mirror case, a prismatic reflective mirror element, and a rigid, molded pivot actuator for moving the case and mirror element between day and night positions for reduced glare. The support bracket has a body with an I-beam configuration in cross section and vibration reducing ribs extending between front and rear flanges adjacent a central web defining the I-beam shape. Resilient clips define grooves for receipt of a windshield mounted button over which the bracket is slid and snapped on. Resilient tension and support members are included along with at least one resilient retainer to keep the bracket on the button. The case includes a peripheral lip allowing snap-in insertion of the mirror element and flexible resilient portions which provide a biasing force urging the pivot actuator into either the day or night position. Preferably, a ball and socket joint extends between the bracket and actuator for adjustment.