The Bach-Gesellschaft Ausgabe (English: "Bach Society Edition") of the complete works of Johann Sebastian Bach was published in a series of 46 volumes from 1851-1899, by the Bach-Gesellschaft and Breitkopf & Härtel in Leipzig. A single supplemental volume was issued in 1926. The last surviving editor of the series died in 1928, and these volumes are public domain worldwide.
The edition varied in quality, depending upon the individual editor in question. The BGA volumes edited by Wilhelm Rust (1822–1892) were generally quite good and often differ little from their modern counterparts found in the Neue Bach Ausgabe, although other editors were less meticulous. In subsequent years lost manuscripts and other source material have been rediscovered, resulting in significant changes. On the other hand, several manuscripts have been lost over the same period, so the BGA remains an important source.