Abstract: A ring binder cover (4) is composed of a pair of thermoplastic sheets (20, 22) superimposed in edge-to-edge relation with a stiffener insert panel (23) disposed therebetween. The insert panel bears two parallel grooves (25, 27) which divide the insert into a spine zone (30) and two cover zones (24, 26). The material of the insert lying at the bottom of the grooves forms a pair of webs (32, 34) which, combined with the adjacent portions of the cover sheets, form hinges between the spine and each cover. The peripheral edge portions (40) of the two thermoplastic sheets are sealed together and provide a sealed envelope for the stiffener insert which defines semi-rigid back and front cover panels of the binder, hingedly connected to a rigid spine.