Abstract: A permanently locking ring binder includes a housing, a pair of hinged plates within the housing, each supporting a plurality of ring segments arranged so that, when the plates are in one position, the ends of the ring segments are spaced apart, so that one can insert loose-leaf papers over the segments, and a second position, in which the ends of opposing ring segments meet, forming closed rings for retaining the papers. The binder has an initially inactive lock which can be activated once papers have been placed in the binder, to prevent movement of the rings to their open position. The lock cannot be manually deactivated.