The 1909 Pittsburgh Pirates season was the 28th season for the Pittsburgh Pirates franchise, during which they won the National League pennant with a record of 110–42 and their first World Series over the Detroit Tigers. Led by shortstop Honus Wagner and outfielder-manager Fred Clarke, the Pirates scored the most runs in the majors. Wagner led the league in batting average, on-base percentage, slugging percentage, and runs batted in. Pirates owner Barney Dreyfuss opened the Pirates' new ballpark, named Forbes Field, on June 30, 1909.