The 1915 Major League Baseball season began on April 14, 1915. The regular season ended on October 7, with the Philadelphia Phillies and Boston Red Sox as the regular season champions of the National League and American League, respectively. The postseason began with Game 1 of the 12th World Series on October 8 and ended with Game 5 on October 13. The Red Sox defeated the Phillies, four games to one.
The competitor Federal League brought an antitrust lawsuit against the National and American Leagues prior to the 1915 season. The parties eventually reached a settlement and the Federal League disbanded after the season.
The 1915 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 for the 1904 season. This format would last until 1919.
Opening Day, April 14, featured all sixteen teams, continuing the trend which started with the 1912 season. The final day of the regular season was on October 7. The World Series took place between October 8 and October 13.