A process cartridge is capable of being carried on a movable guide, which is movable relative to a main assembly of an electrophotographic image forming apparatus and which is provided in the main assembly. The movable guide is movable from a receiving position toward a mount position in interrelation with movement of the movable guide. The cartridge includes an electrophotographic photosensitive drum, a process device actable on the drum, a cartridge frame, and first, second, and third positioning portions. The third positioning portion has a first rotation stopper surface for stopping rotation of the cartridge about the first positioning portion and the second positioning portion by abutting the movable guide.