The 1929 Major League Baseball season began on April 16, 1929. The regular season ended on October 6, with the Chicago Cubs and Philadelphia Athletics as the regular season champions of the National League and American League, respectively. The postseason began with Game 1 of the 26th World Series on October 8 and ended with Game 5 on October 14. The Athletics defeated the Cubs, four games to one.

Red Sox

White Sox

Indians

Tigers

Athletics

Browns

Yankees

Senators

Locations of AL teams for the 1923–1931 MLB seasons
American League

Braves

Robins

Cubs

Reds

Giants

Phillies

Pirates

Cardinals

Locations of NL teams for the 1923–1931 MLB seasons
National League

Babe Ruth hit his 500th career home run this season on August 11 at Cleveland. Game 4 of the World Series featured a historic 10-run rally by the Athletics, nicknamed "The Mack Attack," after the team's manager, Connie Mack.^[1]

This was the last of eight seasons that "League Awards", a precursor to the Major League Baseball Most Valuable Player Award (introduced in 1931), were issued. Only a National League award was given in 1929.

The 1929 schedule consisted of 154 games for all teams in the American League and National League, each of which had eight teams. Each team was scheduled to play 22 games against the other seven teams of their respective league. This continued the format put in place since the 1904 season (except for 1919) and would be used until 1961 in the American League and 1962 in the National League.

Opening Day took place on April 16 and saw eight teams across both leagues play. The final day of the regular season was on October 6. The World Series took place between October 8 and October 14.

The 1929 season saw the following rule changes:

• For all ballparks, foul poles must be constructed to be at least 25 feet above the outer barrier, to aid umpires in calling balls fair or foul. The poles were to be constructed either on top of the grandstand roof, or the outer fence of the ballpark. This was coupled with the home run rule, the interpretation of which follows the early-1920 rule, which states that balls are to be called based on where the ball crosses the outfield fence. This rule now accounts for all balls which leave the ballpark, including those which completely leave the ballpark. The American League would implement this home run rule in 1931.^[2]
• The American League implements the ground rule double rule, which states that balls that bounce over the fence entitle the batter to two bases. The rule would be implemented by the National League in 1931.^[3][4]

• League Award
  • Rogers Hornsby, Chicago Cubs, 2B

• Babe Ruth: On August 11, Babe Ruth became the first player to hit 500 home runs.
• Philadelphia Athletics and Chicago Cubs: First season since 1912 that both pennant winners won by more than 10 games.^[21]
• Philadelphia Athletics: On October 12, during Game 4 of the World Series, the Philadelphia Athletics scored ten runs in the seventh inning to come back from an 8–0 deficit. This was soon dubbed "The Mack Attack," after long-time manager Connie Mack. He commented that it was "The greatest thrill [he] had in 29 years of managing."^[22] At the time, this was a record.

• Miller Huggins, the Yankees manager, died of blood poisoning on September 25.^[23]