A slide fastener lock assembly comprises a slider pull tab having an engaging pin and a lock having a locking lug releasably engageable therewith. The lock has a latch movable toward and away from the locking lug to lock and unlock the pull tab. A lock tumbler is rotatable by a key to releasably lock the latch with the engaging pin. The pull tab and the lock can be joined together simply by flipping the pull tab down with its aperture fitted over the locking lug.