Abstract: A locking assembly suitable for a plurality of sliding doors is disclosed. The assembly includes, at each door, a vertical drop bar in the door jamb with catches for engaging and locking the door at preferably two locations when the bar is lowered and the door is closed. The bar may be lifted by three different means: by a remotely operable motor which may be actuated to rotate a cam through one revolution, thereby lifting up on a rigid horizontal extension of the drop bar; by rotating a key in a key cylinder, which operates a similar rotatable cam to raise the bar; and by an emergency release mechanism including a manually slidable linkage member at the top of the frame, effective when its position is shifted to mechanically lift the drop bar. A deadlock is preferably provided to normally lock the bar in its lower, locking position, the deadlock being releasable upon actuation of any of the three drop bar lifting means.