Abstract: A security system for a license plate, vanity plate or tag includes a bracket for mounting on a vehicle in the space conventionally supporting license plates and a lockable frame interfitting therewith. The bracket has at least one slot for engaging a tab carried by the frame, and another slot for engaging a locking member extending from a lock. The frame has apertures for supporting a license plate, and the frame and license plate are readily removable as a unit for storage in a high security area to prevent theft of the license plate, as well as to deter the installation of an unauthorized license plate as often hapens when the vehicle will be stolen. The system can be mounted with the lock on the top or bottom side, and one embodiment includes an open area in the frame opposite the lock. The lock is preferably a cam lock and is positioned to deter tampering. A bracket has upper and lower planar portions which may be angled with respect to a main planar portion.