Abstract: Disclosed is a ribbon tape cartridge assembly, the cartridges being adapted for mating in superimposed overlapping relation, bottom to bottom to form the assembly. Slots in tabs which project from the plane of one of the bottom surfaces of one of the cartridges coact with fins on the other of the cartridges, the fins movable into the slot for an interference fit with at least a portion of the tab. Shoulders on each of the cartridges also coact for limiting relative movement of the cartridges in a first direction with respect to each other. One of the cartridges is provided with a camming surface and a cam follower is provided the other of the cartridges, the cam and cam follower being engageable to effect relative movement between the cartridges in the first direction until the shoulders abutt one another inhibiting further relative motion.