Double-A (or Class AA) is the second highest level of play in Minor League Baseball (MiLB) in the United States after Triple-A. There are thirty Double-A teams in three leagues at this classification: the Eastern League, Southern League, and Texas League. The modern Double-A classification was created in 1946 with the renaming of Class A1, which then contained the Texas League and the Southern Association. After the Southern Association disbanded in 1961, the Eastern League and the original South Atlantic "Sally" League were bumped up to Double-A in the 1963 minor league reorganization. The Sally League changed its name to the Southern League in 1964.
The Double-A classification usually hosts developing players that have been part of professional baseball for only a couple of years. These players can get to the Double-A level by earning a promotion from any of the Single-A or Rookie leagues. Players often advance directly to the Major League Baseball from this level, as the level of competition is higher. Because they are still advancing in their careers, the average talent level of Double-A may be higher than in Triple-A, which has minor and major league veterans who have been in the minor league system for a longer period of time and may have stagnated. A small handful of players might be placed in Double-A to start, usually veterans from foreign leagues or top prospects out of college. The step up to the Double-A level can be one of the hardest promotions for such players because it is the level at which pitchers need to have a good off-speed pitch in their repertoires. In addition, it is the level where fastball-only hitters need to learn how to hit off-speed pitches, or their hopes of advancing to the majors will diminish. Major league teams sometimes send players to play at the Double-A level to rehabilitate from injuries.
Because players are not moving back and forth from the major leagues at this level, the rosters tend to be more stable. Fans of Double-A teams have a longer amount of time to get acquainted with the players, which helps create a better relationship between the team and its fans.
Unlike the major league and the Triple-A level, all three Double-A leagues have their season divided into two parts, after the Eastern League announced that it would move to that system starting in 2019. One team may clinch a spot in the playoffs by winning the division in first half of the season. The teams' records are then cleared and another team will also clinch a playoff slot during the second half. Wild cards are used to fill out the remaining teams. Usually, four teams qualify for the league playoffs. This system is used at the Class A level as well.
Each of the three leagues holds its own midseason All-Star Game. From 1991 to 2002, the three combined to hold the Double-A All-Star Game between teams of American League-affiliated All-Stars and National League-affiliated All-Stars.
As a part of professional baseball's pace-of-play initiatives implemented in 2015, 20-second pitch clocks entered use at Double-A stadiums in 2015. In 2018, the time was shortened to 15 seconds when no runners are on base. Other significant changes implemented in 2018 include beginning extra innings with a runner on second base and limiting teams to eight mound visits during a nine-inning game. Beginning in 2019, the number of mound visits is reduced to seven, and pitchers are required to face a minimum of three consecutive batters until the side is retired or the pitcher becomes injured and is unable to continue playing.
- "Teams by League and Classification". Minor League Baseball. Retrieved November 8, 2020.
- "What is Double AA Baseball?". SportingCharts. 2014. Retrieved March 19, 2015.
- Moore, Jeff (July 2, 2013). "Understanding Minor League Levels". The Hardball Times. Retrieved March 18, 2015.
- Santelli, Robert; Santelli, Jenna (2010). The Baseball Fan's Bucket List: 162 Things You Must Do, See, Get, and Experience Before You Die. Running Press. p. 218. ISBN 9780762438556.
- Knight, Graham (September 17, 2010). "NYSEG Stadium". Baseball Pilgrimages. Retrieved May 4, 2015.
- Mock, Joe. "Dunkin' Donuts Park". www.baseballparks.com. Grand Slam Enterprises, Inc. Retrieved September 27, 2017.
- "2012 New Hampshire Fisher Cats Media Guide" (PDF). Minor League Baseball. April 9, 2012. Retrieved May 4, 2015.
- Knight, Graham (July 6, 2010). "Hadlock Field – Portland Sea Dogs". Baseball Pilgrimages. Retrieved May 4, 2015.
- Leon, Matt (May 17, 2011). "Minor League Ballpark Guide". KYW. Philadelphia. Retrieved May 4, 2015.
- "Akron RubberDucks Canal Park". Minor League Baseball. November 27, 2012. Retrieved September 27, 2017.
- "2012 Altoona Curve Media Guide". Minor League Baseball. 2012. Retrieved May 4, 2015.
- "Bowie Baysox Baysox/Stadium Info". Minor League Baseball. March 11, 2009. Retrieved May 4, 2015.
- "Jerry Uth Park". Erie County Convention Center Authority. Archived from the original on July 30, 2012. Retrieved August 3, 2012.
- Reichard, Kevin (June 28, 2010). "Metro Bank Park / Harrisburg Senators". Ballpark Digest. Retrieved May 4, 2015.
- O'Connor, John (March 27, 2010). "Bleacher Banners Give Diamond New Look, Fewer Seats". Richmond Times-Dispatch. Retrieved February 23, 2014.
- "Regions Field Birmingham Barons". Minor League Baseball. January 27, 2012. Retrieved May 4, 2015.
- Knight, Graham (July 27, 2010). "AT&T Field". Baseball Pilgrimages. Retrieved May 4, 2015.
- Knight, Graham. "The Ballpark at Jackson". Baseball Pilgrimages. Retrieved May 4, 2015.
- Gattis, Paul (April 15, 2019). "Countdown is on: 1 year from today until first Trash Pandas game in Madison". AL.com. Retrieved September 5, 2019.
- Reichard, Kevin (May 1, 2015). "Smokies Park / Tennessee Smokies". Ballpark Digest. Retrieved May 4, 2015.
- Harris, Chris (February 12, 2015). "A Walking Tour of MGM Park". Minor League Baseball. Retrieved May 4, 2015.
- Knight, Graham (August 16, 2003). "Baseball Grounds of Jacksonville – Jacksonville Suns". Baseball Pilgrimages. Retrieved February 23, 2014.
- "Mississippi Braves Stadium Information". Minor League Baseball. November 13, 2008. Retrieved May 4, 2015.
- "Riverwalk Stadium Information". Minor League Baseball. February 25, 2013. Retrieved May 4, 2015.
- Pillon, Dennis (April 20, 2012). "Pensacola's Class AA Baseball Fever Still Going Strong". Press-Register. Mobile. Retrieved May 4, 2015.
- "Dickey-Stephens Park". Arkansas Diamonds: The Ballparks of Arkansas and Their History. Archived from the original on May 5, 2015. Retrieved September 22, 2017.
- Bergeron, Angela (2008). "Feature Story - August 2008". Engineering News-Record. McGraw-Hill. Archived from the original on February 27, 2014. Retrieved September 22, 2017.
- Mock, Joe. "Hammons Field in Springfield, Missouri". Baseball Parks. Retrieved September 22, 2017.
- "ONEOK Field". Tulsa Sports Commission. 2010. Retrieved May 4, 2015.
- Reichard, Kevin (April 10, 2019). "Sod Poodles Launch Crowd-Pleasing Ballpark". Ballpark Digest. August Publications. Retrieved April 10, 2019.
- Goldberg-Strassler, Jesse (November 19, 2012). "Whataburger Field / Corpus Christi Hooks". Ballpark Digest. Retrieved May 4, 2015.
- Goldberg-Strassler, Jesse (November 14, 2012). "Dr Pepper Ballpark / Frisco RoughRiders". Ballpark Digest. Retrieved May 4, 2015.
- "Security Bank Ballpark". Stadiums USA. Archived from the original on May 8, 2016. Retrieved September 22, 2017.
- "Texas League Playoff Procedures". Retrieved March 28, 2015.
- "Eastern League Playoff Procedures". Retrieved March 28, 2015.
- "Southern League Playoff Procedures". Retrieved March 28, 2015.
- "Important Dates". Minor League Baseball. Retrieved April 24, 2020.
- "SL Sets First All-Star Tilt". The Orlando Sentinel. Orlando. July 11, 1991. p. B-4 – via Newspapers.com.
- Gonzalez, Roberto (July 11, 2002). "End Comes in Seventh". Hartford Courant. Hartford. p. C1 – via Newspapers.com.
- Jackson, Josh (January 15, 2015). "Triple-A, Double-A to Implement Pitch Clock". MILB.com. Retrieved April 20, 2015.
- "MiLB announces pace-of-play rules for 2018". MILB.com. March 14, 2018. Retrieved March 15, 2018.
- "MiLB announces pace-of-play rules for 2019". MILB.com. March 29, 2019. Retrieved March 30, 2019.