Abstract: A reinforcing plate for reinforcing a doorjamb to prevent break-ins and particularly kick-ins of the door by unauthorized persons is mounted in back of the doorjamb in the space between the jamb and the door frame. In order to install the reinforcing plate behind the doorjamb, the interior trim strip is removed from the door frame and the reinforcing plate is mounted behind the doorjamb, preferably by the use of shims to temporarily jam the plate between the doorjamb and the door frame. While the reinforcing plate is temporarily secured by a wedging means against the back of the door frame, holes are drilled in the door frame and through the reinforcing plate using appropriately-sized drill bits. Self-tapping threaded screws are then passed through the doorjamb and screwed tightly into the reinforcing plate the attach the plate to the doorjamb and reinforce the jamb. As an alternative, special fastenings are provided to fasten the striker plate to the reinforcing plate.