InMajor League Baseball, theAmerican League Division Series (ALDS) determines which two teams from theAmerican League will advance to theAmerican League Championship Series. The Division Series consists of two best-of-five series, featuring each of the two division winners with the best records and the winners of thewild-card play-off.

The Division Series was implemented in 1981 as a one-off tournament because of amidseason strike, with the first place teams before the strike taking on the teams in first place after the strike. In the split 1981 season, the Kansas City Royals reached the postseason with a losing record (50–53) under the first-half/second-half format.^[1]

Teams with sub-.500 records have also qualified in later years during expanded formats, including the 2020 Milwaukee Brewers (29–31) and 2020 Houston Astros (29–31).^[2][3][4]

In 1994, it was returned permanently whenMajor League Baseball (MLB) restructured each league into three divisions, but with a different format than in 1981. Each of the division winners, along with onewild card team, qualifies for the Division Series. Despite being planned for the 1994 season, the postseason was cancelled that year due to the1994–95 Major League Baseball strike. In 1995, the first season to feature a division series, the Western Division championSeattle Mariners defeated the wild cardNew York Yankees three games to two, while the Central Division championCleveland Indians defeated the Eastern Division championBoston Red Sox in a three-game sweep.

From 1994 to 2011, the wild card was given to the team in the American League with the best overall record that wasnot a division champion. Beginning with the2012 season, a second wild card team was added, and the two wild card teams play a single-game playoff to determine which team would play in the ALDS. For the2020 Major League Baseball season only, there was an expanded playoff format, owing to an abbreviated 60-game regular season due to theCOVID-19 pandemic. Eight teams qualified from the American League: the top two teams in each division plus the next two best records among the remaining teams. These eight teams played a best-of-three-game series to determine placement in the ALDS. The regular format returned for the 2021 season.

The New York Yankees lead all franchises in ALDS appearances and series victories.^[5] The Astros had been in the National League through 2012, and had played in theNational League Division Series (NLDS) seven times. The Astros are the only team to win the ALDS in six consecutive seasons. The Yankees' record of four consecutive victories was broken by the Astros with their victory in the 2021 ALDS against theChicago White Sox.

The ALDS is a best-of-five series where the divisional winner with the best winning percentage in the regular season hosts the winner of theWild Card Series between the top two wild card teams in one matchup, and the divisional winner with the second best winning percentage hosts the winner of the series between the lowest-seeded divisional winner and the lowest-seeded wild card team.^[6] (From 2012 to 2021, the wild card team was assigned to play the divisional winner with the best winning percentage in the regular season in one series, and the other two division winners met in the other series.^[7] From 1998 to 2011, if the wild-card team and the division winner with the best record were from the same division, the wild-card team played the division winner with the second-best record, and the remaining two division leaders played each other.) The two series winners move on to the best-of-seven ALCS. According toNate Silver, the advent of this playoff series, and especially of the wild card, has caused teams to focus more on "getting to the playoffs" rather than "winning the pennant" as the primary goal of the regular season.^[8]

From 2012 to 2021, the wild card team that advances to the Division Series was to face the number 1 seed, regardless of whether or not they are in the same division.^{[9][10][11][12]} The two series winners move on to the best-of-seven ALCS. Beginning with the 2022 season, the winner between the lowest-ranked division winner and the lowest-ranked wild card team faces the number 2 seed division winner in the Division Series, while the 4 v. 5 wild card winner still faces the number 1 seed, as there is no reseeding even if the 6-seeded wild card advances. Home-field advantage goes to the team with the better regular-season record (or head-to-head record if there is a tie between two or more teams), except for the wild-card team, which never receives the home-field advantage.^[13][14][15]

Beginning in 2003, MLB has implemented a new rule to give the team from the league that wins the All-Star Game with the best regular season record a slightly greater advantage. In order to spread out the Division Series games for broadcast purposes, the two ALDS series follow one of two off-day schedules. Starting in 2007, after consulting theMLBPA, MLB has decided to allow the team with the best record in the league that wins the All-Star Game to choose whether to use the seven-day schedule (1-2-off-3-4-off-5) or the eight-day schedule (1-off-2-off-3-4-off-5). The team only gets to choose the schedule; the opponent is still determined by win–loss records.

Initially, the best-of-5 series was played in a 2–3 format, with the first two games set at home for the lower seed team and the last three for the higher seed.^[16][17] Since1998, the series has followed a 2–2–1 format,^[18] where the higher seed team plays at home in Games 1 and 2, the lower seed plays at home in Game 3 and Game 4 (if necessary), and if a Game 5 is needed, the teams return to the higher seed's field. When MLB added a second wild card team in2012, the Division Series re-adopted the 2–3 format due to scheduling conflicts. However, it reverted to the 2–2–1 format starting the next season,2013.^[19]

Under MLB’s expanded 12-team postseason introduced in 2022, each league sends three division winners and three Wild Card teams. The two division winners with the best records receive byes into the Division Series; the remaining division winner (No. 3 seed) and the three Wild Cards (Nos. 4–6) play best-of-three Wild Card Series, hosted entirely by the higher seed. The ALDS then follows a fixed bracket with no reseeding, and is played in a best-of-five, 2–2–1 format with the higher seed hosting Games 1–2 and 5 (if necessary).^[20]

• The Houston Astros advanced out of the ALDS in seven consecutive seasons (2017–2023), reaching the ALCS each year in that span.^[21][22]

In the sortable table below, teams are ordered first by number of wins, then by number of appearances, and finally by year of first appearance. In the "Season(s)" column,bold years indicate winning appearances.

• National League Division Series (NLDS)
• List of American League pennant winners
• List of National League pennant winners
• List of World Series champions
• MLB division winners
• MLB postseason

• Baseball-Reference.com - annual playoffs
• MLB.com - MLB's Division Series historical reference - box scores, highlights, etc.

• American League Division Series
• Recurring sporting events established in 1994
• Annual events in Major League Baseball

• Articles with short description
• Short description is different from Wikidata
• Articles with hCards