Abstract: A constant velocity universal ball joint has an outer joint part with substantially longitudinally extending outer ball tracks and an inner joint part with substantially longitudinally extending inner ball tracks. The tracks in the outer joint part and inner joint part are positioned radially opposite one another to form a pair and, in each case, jointly receiving a torque-transmitting ball. A ball cage includes circumferentially distributed cage windows, which hold the balls in a common plane and guides them on to the angle-bisecting plane when the joint is articulated. The cage windows, if viewed in the circumferential direction, narrow at their ends. Opposed flanks of the cage windows jointly form a stop relative to the respective balls if there occurs a relative circumferential displacement between the ball cage and balls.