Abstract: A connector system for demountable wall modules, including a pair of adjoining vertical channel members having mating structure. The channel members are cut from the same extrusion, and one member is inverted with respect to the other. The mating structure which that provides includes an outwardly extending flange having a mating protrusion, a central wall, and a U-shaped rail having a mating cavity. The mating protrusion on one channel member is positioned to fit within the mating cavity of the other channel member, and vice versa. The central walls are slightly offset from a central plane of the panels to lie in an overlapped relationship. One or more locking keys are inserted through slots in the extending flanges to bias the flange away from the central wall of the opposed channel member. In this manner, the mating protrusions are held within the mating cavities to securely fasten the two panels together.