Abstract: An adjustable tether for joining the upper arms of a golfer together to coordinate the relative motion of the arms of the golfer during his swing. The arm joining tether comprises first and second generally Y-shaped flexible straps each having a stem portion which is bifurcated so as to terminate in branch portions which may be joined by suitable fasteners to form arm engaging loops. The stem portions may also be joined by a suitable two-element separable fastener and when in use, the joined stem portions span the chest of the user. It has been found that mating hook and loop type fasteners are ideally suited for joining the Y-shaped flexible strap members, one to the other, and in coupling the branch portions of each to form the aforesaid arm engaging loops. Further, each of the individual Y-shaped strap members is marked with a suitable graduated marking to facilitate the sizing of the device to golfers of different physical size.