Rules can be found at The World Tetherball Association based in Palm Springs California. The game begins when one player serves the ball, usually by hitting it off the post, or after the opposing player serves it he can not hit it until the other player touches it. The opposing player then attempts to return the serve by hitting it in the opposite direction. The object is to hit the ball in such a way that one's opponent will be unable to alter the ball's direction. This gives the server an advantage since the server has more control over the ball from the beginning. It is generally acceptable to hit the ball with either the fist or the open hand or swing. The Players pick if a "cherrybomb" is legal but is usually legal in official games.

A player can commit a violation by stepping onto his opponent's half of the pole, by catching and throwing the ball (a "crossy"), by striking the rope instead of the ball (a "ropey"), by hitting the ball twice before it has either circled the pole or been returned by the opponent or, in some variants, struck the pole (a "double touchie"). Generally, after a violation occurs, the game pauses and the ball is returned to the position it was in before the violation; the number of wraps around the pole is re-created (or a penalty-wrap is awarded to the player who did not commit the foul). The player who did not commit the violation then serves the ball. If, however, the violation appears to be intentional, it may result in loss of game.

The game ends when one player hits the ball around the pole in their own direction as far as it will go, so that the ball hits the pole. In addition, the ball must strike the pole with the final wrap above a line marked on the pole. A 5-foot-high (1.5 m) mark is satisfactory, though a lower mark might be used for younger players. A match can go on for at least 2 or more games.

CREDIT TO :: ( http://en.wikipedia.org/wiki/Tetherball )