The 1906 major league baseball season began on April 12, 1906. The regular season ended on October 7, with the Chicago Cubs and Chicago White Sox as regular season champions of the National League and American League, respectively. The postseason began with Game 1 of the third modern World Series on October 9 and ended with Game 6 on October 14. The White Sox defeated the Cubs, four games to two.
The 1906 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.
National League Opening Day took place on April 12 with all teams playing, while American League Opening Day did not take place until April 14 with four teams playing. The final day of the regular season was on October 7. The World Series took place between October 9 and October 14.
July 4 – Mordecai Brown of the Chicago Cubs defeats Lefty Leifield of the Pittsburgh Pirates, 1–0, in which both pitchers allowed only one hit. Leifield recorded the only hit for Pittsburgh. This was the first double one-hitter in MLB history in the modern era (since 1901), and one of four double one-hitters ever pitched.[18]