Sister Sledge is an American musical vocal group from Philadelphia, Pennsylvania. Formed in 1971, the group consisted of sisters Debbie, Joni, Kim and Kathy Sledge. The siblings achieved international success at the height of the disco era. The year 1979 saw the release of their breakthrough album We Are Family, which peaked at number three on the US Album Chart and included the 1979 US top ten singles "He's the Greatest Dancer" and "We Are Family". A third single, "Lost in Music", reached the US top forty. "We Are Family" earned a Grammy Award nomination for Best R&B Performance by a Duo or Group with Vocal.