The invention is a chain locking mount for mounting the roller chain portion of a roller blind to a support surface such as a wall or window frame. The mount is configured to prevent the chain from being operated when the mount loosens from the support surface. The mount includes a housing with an aperture formed therein which is dimensioned to permit the roller chain to pass through the aperture. The mount further includes a lock member mounted adjacent the aperture, the lock member being movable between a locked position wherein the chain is prevented from moving through the aperture and an open position wherein the chain is free to move through the aperture. The mount is secured to the surface by a screw, the screw being coupled to the lock mechanism to retain the lock member in its open position when the screw is tightened to the surface. The lock member is biased towards its locked position so that the lock member moves towards its locked position when the screw is loosened from the surface.