Abstract: A device for controlling a bowling ball having a thumb hole therein, in which a sleeve-like member for slipping on the bowler's thumb and into the hole of the ball, has one or more friction pads on the outside of the member adjacent the back of the thumb when disposed in the member for transmitting a control force between the thumb and the bowling ball. The sleeve-like member is held on the thumb preferably by a strap attached to the member and extending around the wrist of the bowler, and a cylindrical sleeve is disposed in and secured in the thumb hole of the bowling ball. The sleeve-like member may have a plurality of removable and replaceable friction pads, and the sleeve may have a friction pad along the internal surface thereof for engagement by the friction pads on the sleeve-like member.