Agnetha Fältskog (born April 5th, 1950): vocals Björn Ulvaeus (born April 25th, 1945): guitars, vocals Benny Andersson (born December 16th, 1946): keyboards, vocals Anni-Frid Lyngstad (born November 15th, 1945): vocals Internationally successful Swedish pop group, active from 1972 until 1983. The most commercially successful artists of the 1970s, their biggest hits include Dancing Queen, Fernando, Waterloo, Chiquitita, Mamma Mia, and Take A Chance On Me. Sales figures for the group are widely varying, with the official estimate at 370 million records. Their music has seen a resurgence in interest in part due to the release of their multi-platinum greatest hits album "ABBA Gold" in 1992 and a general revival in interest in disco and '70s music around the same time. Their music gained even greater visibility with the jukebox musical "Mamma Mia!