What Is a Ground-Rule Double in Baseball?

A ground-rule double is a two-base award to the batter when a fair ball goes out of play without clearing the fence on the fly for a home run. The most common example is a ball that bounces in fair territory and then hops over the outfield wall. The ball is ruled dead, the batter gets second base, and all runners advance two bases from the base they occupied at the pitch.

Exactly two bases, measured from where each runner was at the time of the pitch — not from where they happened to be running. So a runner on first goes to third, and a runner on second scores. A runner on second cannot score if he was only on first, even if he was rounding third when the ball went out. The dead-ball rule caps the advance at two bases for everyone.

The name comes from the idea of a ballpark's ground rules — the venue-specific rules for balls that hit quirky features. Many such plays (a ball stuck in the outfield wall padding, lost in Wrigley Field's ivy, or lodged under a fence) are two-base awards under those local rules. Over time 'ground-rule double' became the common name even for the standard bounce-over-the-fence double, which is actually a leaguewide rule.

No. A fair ball that bounces in the field and then goes over the fence is a ground-rule double, worth two bases, not a home run. To be a home run, the ball must clear the fence in fair territory on the fly without touching the ground first. The bounce is the key difference: on the fly it's a homer, off a bounce it's a double.

No. Because the award is exactly two bases from the pitch, a runner who started on first can only reach third, even on a deep ball. This sometimes frustrates the batting team when a runner was fast enough to score on a live ball, but the dead-ball rule takes that possibility away. It can also help the defense by stopping a run that would otherwise have scored.

They are often used to mean the same thing. Purists note that a true 'ground-rule' double comes from a park's specific ground rules, while the bounce-over-the-fence double is technically an 'automatic double' under the universal rules. In everyday use, both are called ground-rule doubles. Either way the effect is identical: the batter gets two bases and the ball is dead.

It is one of several dead-ball and baserunning rules that shape how runners advance, alongside [tagging up](/what-is-tagging-up-in-baseball/), the [dropped third strike](/dropped-third-strike-rule/), and the [infield fly rule](/infield-fly-rule/). Each covers a specific situation, and together they account for many of the stoppages and odd advances that puzzle newer fans.