The 1966 Major League Baseball season was contested from April 11 to October 9, 1966. The Braves played their inaugural season in Atlanta, following their relocation from Milwaukee. Three teams played the 1966 season in new stadiums. On April 12, the Braves ushered in Atlanta–Fulton County Stadium with the Pittsburgh Pirates taking a 3–2 win in 13 innings. One week later, Anaheim Stadium opened with the California Angels losing to the Chicago White Sox, 3–1 in the Angels' debut following their move from Los Angeles to nearby Orange County. On May 8, the St. Louis Cardinals closed out old Sportsman's Park/Busch Stadium I with a 10–5 loss to the San Francisco Giants before opening the new Busch Memorial Stadium four days later with a 4–3 win in 12 innings over the Atlanta Braves.

The Atlanta Braves are an American professional baseball team based in the Atlanta metropolitan area. The Braves compete in Major League Baseball (MLB) as a member club of the National League (NL) East Division. The Braves were founded in Boston, Massachusetts, in 1871, as the Boston Red Stockings. The club was known by various names until the franchise settled on the Boston Braves in 1912. The Braves are the oldest continuously operating professional sports franchise in North America.