Abstract: A ring binding mechanism, for use with a binder or book having a backbone, has a curved housing which pivotally retains a pair of hinge plates carrying binding rings. A control bar, moveable between a first position and second position, is slideably affixed to the housing independent of the backbone by means of retaining rivets extending through the housing and through a slotted opening in the control bar. The control bar includes cam surfaces positioned to force the hinge plates inward towards the housing to close the binding rings as the control bar is moved to the first position, and cam surfaces positioned to force the hinge plates towards the housing to open the binding rings as the control bar is moved to the second position. The control bar further includes ratchet grooves which engage an intermeshing tongue to lock the control bar in a closed position.