A portable lock for locking a door has a lock bar for insertion and retention between a door jamb and the latch side of a door. A housing is movable along the lock bar between a retracted position enabling pivoting movement of the door about its hinge between closed and open positions and a forward position engageable with the door in the closed position. A lever arm locking mechanism is movable between first and second positions for locking the housing in the forward position to prevent movement of the door from the closed position to the open position.