18-1. By Outside Agency
If a ball at rest is moved by an outside agency, there is no
penalty and the ball must be replaced.
(Player’s ball at rest moved by another ball – see Rule 18-5)
18-2. By Player, Partner, Caddie or Equipment
a. General
When a player’s ball is in play, if:
(i) the player, his partner or either of their caddies lifts or
moves it, touches it purposely (except with a club in the
act of addressing it) or causes it to move except as
permitted by a Rule, or
(ii) equipment of the player or his partner causes the ball
to move,
the player incurs a penalty of one stroke. If the ball is moved,
it must be replaced unless the movement of the ball occurs
after the player has begun the stroke or the backward
movement of the club for the stroke and the stroke is made.
Under the Rules there is no penalty if a player accidentally
causes his ball to move in the following circumstances:
• In searching for a ball in a hazard covered by loose
impediments or sand, for a ball in an abnormal ground
condition or for a ball believed to be in water in a water
hazard – Rule 12-1
• In repairing a hole plug or ball mark – Rule 16-1c
• In measuring – Rule 18-6
• In lifting a ball under a Rule – Rule 20-1
• In placing or replacing a ball under a Rule – Rule 20-3a
• In removing a loose impediment on the putting green –
Rule 23-1
• In removing movable obstructions – Rule 24-1
b. Ball Moving After Address
If a player’s ball in play moves after he has addressed it (other
than as a result of a stroke), the player is deemed to have
moved the ball and incurs a penalty of one stroke. The ball
must be replaced unless the movement of the ball occurs after
the player has begun the stroke or the backward movement of
the club for the stroke and the stroke is made.
18-3. By Opponent, Caddie or Equipment in Match Play
a. During Search
If, during search for a player’s ball, an opponent, his caddie
or his equipment moves the ball, touches it or causes it
to move, there is no penalty. If the ball is moved, it must
be replaced.
b. Other Than During Search
If, other than during search for a player’s ball, an opponent,
his caddie or his equipment moves the ball, touches it
purposely or causes it to move, except as otherwise provided
in the Rules, the opponent incurs a penalty of one stroke. If the
ball is moved, it must be replaced.
(Playing a wrong ball – see Rule 15-3)
(Ball moved in measuring – see Rule 18-6)
18-4. By Fellow-Competitor, Caddie or Equipment in
Stroke Play
If a fellow-competitor, his caddie or his equipment moves
the player’s ball, touches it or causes it to move, there is
no penalty If the ball is moved, it must be replaced.
(Playing a wrong ball – see Rule 15-3)
18-5. By Another Ball
If a ball in play and at rest is moved by another ball in motion
after a stroke, the moved ball must be replaced.
18-6. Ball Moved in Measuring
If a ball or ball-marker is moved in measuring while
proceeding under or in determining the application of a Rule,
the ball or ball-marker must be replaced. There is no penalty
provided the movement of the ball or ball-marker is directly
attributable to the specific act of measuring. Otherwise, the
provisions of Rules 18-2a, 18-3b or 18-4 apply.
Match play – Loss of hole; Stroke play – Two strokes.
*If a player who is required to replace a ball fails to do so, he
incurs the general penalty for breach of Rule 18. There is no
additional penalty under Rule 18, except in the case of a
wrongly substituted ball (Rule 15-2).
Note 1: If a ball to be replaced under this Rule is not
immediately recoverable, another ball may be substituted.
Note 2: If the original lie of a ball to be placed or replaced has
been altered, see Rule 20-3b.
Note 3: If it is impossible to determine the spot on which a ball
is to be placed, see Rule 20-3c.