National League Championship Series

The National League Championship Series (NLCS) is a best-of-seven series played in October in the Major League Baseball postseason that determines the winner of the National League (NL) pennant. The winner of the series advances to play the winner of the American League (AL) Championship Series (ALCS) in the World Series, Major League Baseball's championship series.

Prior to 1969, the National League champion (the "pennant winner") was determined by the best win-loss record at the end of the regular season. There were four ad hoc three-game playoff series due to ties under this formulation (in 1946, 1951, 1959, and 1962). (The American League had to resolve a tie in 1948, but used a single-game playoff.)

A structured postseason series began in 1969, when both the National and American Leagues were reorganized into two divisions each, East and West. The two division winners within each league 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.

The NLCS and ALCS, since the expansion to seven games, 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. Home field advantage is given to the team that has the better record, with the exception that the team that made the postseason as the Wild Card team cannot get home field advantage. From 1969 to 1993, home field advantage was alternated between divisions each year regardless of regular season record and from 1995 to 1997 home field advantage was predetermined before the season.

In 1981, a divisional series was held due to a split season caused by a players' strike.

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