Abstract: A security door system includes an actuator mechanism housed in a box-like, closed housing to minimize the possibility of tampering with the actuator mechanism such as would permit unlawful entry through the door. The actuator mechanism drives one or more, and illustratively two, bolts which extend horizontally across the door. One of the bolts enters a receiver in the jamb along the edge of the door opposite the hinged edge. The other bolt enters a receiver provided in the jamb along the hinged door edge. The security door system further includes a jamb and frame construction in which the jamb and surrounding frame cooperate to provide the bolt receivers. A metal reinforcing plate which is fixed to the frame by long wood screws, or the like, forms a wall of the receiver. This metal walled, deep receiver is less susceptible to damage by tampering, such as by springing the jamb or ramming against the door, than prior art security door systems.