Abstract: A golf taining device is mounted on the bill of a golfer's headpiece and is operable to provide clear evidence of improper head or neck movement during the golf swing, and foster coordinated rotational movement of shoulders, torso and hips. The device includes a ball and a base member consisting of a cup shaped ball carrying seat structure having a ball retaining wall having side walls of a reduced height but of a size and disposition to normally keep the ball in the seat structure even during the address of a ball to be struck and during a correct swing. The ball is tethered to the base member by a flexible cord and the wall is of insufficient size to prevent movement of the ball out of the seat structure when the base member is moved or tilted in an accented way by improper head or neck movement during the golf swing.