Vehicle interior mirror assembly

A vehicle interior rearview mirror assembly comprises a housing (10) having a front end (12) releasably attached to the interior surface of the vehicle windshield and a rear end (44) having a ball (32) and socket joint (36) for a rearview mirror unit (34). An internal wall (16) subdivides the interior of the housing into first and second compartments (18,20). The first compartment (18) contains a rain sensor (26) which is preferably biased into contact with the windshield, and the second compartment (20) contains a further electrical component such as a compass sensor accessible through a side opening. A removable cover (40) mates with the housing (10) around the opening and extends along the windshield towards the vehicle header. Electrical leads for the rain sensor (26) and the component (30) are routed under the cover (40) to the header.