<P> The American League Championship Series (ALCS) is a best - of - seven series played in October in the Major League Baseball postseason that determines the winner of the American League (AL) pennant . The winner of the series advances to play the winner of the National League (NL) Championship Series (NLCS) in the World Series, Major League Baseball's championship series . </P> <P> It started in 1969, when the AL reorganized into two divisions, East and West . The winners of each division played each other in a best - of - five series to determine who would advance to the World Series . In 1985, the format changed to best - of - seven . In 1994, the league was restructured into three divisions, with the three division winners and a wild - card team advancing to a best - of - five postseason round, known as the American League Division Series (ALDS). The winners of that round then advanced to the best - of - seven ALCS . In 2012, the playoffs were expanded again so that two wild card teams face off in a one - game wild card round to determine which team advances to the division series, with the playoffs then continuing as it had before 2012 (though with the possibility of a fifth seed being in the playoffs and a fourth seed being out) after the end of the wild card round . This is the system currently in use . </P> <P> The ALCS and NLCS, since the expansion to best - of - seven, are always played in a 2--3--2 format: Games 1, 2, 6, and 7 are played in the stadium of the team that has home field advantage, and Games 3, 4, and 5 are played in the stadium of the team that does not . The series concludes when one team records its fourth win . Since 1998, home field advantage has been given to the team that has the better regular season record, unless that team happens to be the Wild Card team . In that case, the other team gets home field advantage, because by rule the Wild Card team is never allowed home field advantage in a Division Series or LCS . In the event that both teams have identical records in the regular season, home field advantage goes to the team that has the winning head - to - head record . From 1969 to 1993, home field advantage alternated between the two divisions, and from 1995 to 1997 home field advantage was determined before the season . </P> <P> The Milwaukee Brewers, an American League team between 1969 and 1997, and the Houston Astros are the only franchises to play in the ALCS and NLCS . The Astros are the only team to have won both the National and American League Championship Series . </P>

Who gets home field advantage in the alcs