Joni Sledge of Philadelphia's 'We Are Family' group Sister Sledge has died

Joni Sledge (second from left) appears with niece Camille Sledge (left), producer Rodney Jerkins, and Joni Sledge's cousin Amber Sledge at the "We Are Family 2006 - All-Star Katrina Benefit CD and Documentary DVD Launch" in Century City, Calif. in 2006.

Joni Sledge of the Philadelphia sibling group Sister Sledge, best known for “We Are Family,” the 1979 sing-along anthem of female and familial solidarity, has died. She was 60.

Ms. Sledge died of unknown causes at her home in Phoenix on Friday, according to her publicist, Biff Warren, who said she had not been ill.   

Sister Sledge was formed in 1971 with Joni, the second eldest of four siblings, together with sisters Debbie, Kim, and Kathy. They came from a family of performers: father Edwin Sledge was a tap dancer and mother Florez an actress, and they studied music with their grandmother Viola Williams, an opera singer with whom they sang at the Williams Temple Christian Methodist Episcopal Church in the Grays Ferry section of South Philadelphia as children.

Sister Sledge struggled though the '70s, scoring minor hits in Europe. "We’d been working in Atlantic City, 4 in the afternoon to 4 in the morning, six sets, opening for everybody that came through – the Emotions, Bill Withers, the Pointer Sisters,” Joni Sledge told the Guardian last year. “And they were all really encouraging: 'You girls are really good, you should stick with it.' "

Their fortunes changed when their label, Atlantic Records, hooked them up with Nile Rodgers and Bernard Edwards, the songwriters and producers behind the disco band Chic. They scored their first hit with “He’s the Greatest Dancer,” which hit No. 9 on the Billboard charts and was later sampled by Will Smith on his 1997 hit “Gettin' Jiggy Wit’ It.”

The signature song came with “We Are Family,” the sing-along celebration of sisterhood that was the group’s calling card for decades. "Recording it was like a one-take party – we were just dancing and playing around and hanging out in the studio when we did it,” Joni Sledge said last year.

With lead vocals sung by then-19-year-old Kathy Sledge, it went to No. 2 on the pop charts in 1979 and was further popularized after being adopted as the theme song by the Pittsburgh Pirates during their run to the World Series title that year. Over the years, the song has been covered by many artists, including the Spice Girls, the Corrs, Babes in Toyland, and, in a version produced by Rodgers, characters from Sesame Street, The Muppet Show, and SpongeBob SquarePants.

The We Are Family album scored a third hit with “Lost in Music,” with Joni singing the lead: “We’re lost in music, I feel so alive / We’re lost in music, I quit my 9 to 5.” The song topped the Billboard dance charts and was later covered by the British post-punk band the Fall.

"Joni sang that song, and the lyrics were so reflective of her personality. She’s like that to this day: It’s all of our passion, but she’s really focused, she’s all up in that music,” Debbie Sledge told the Guardian. “The words are about determination, not giving up, so they kind of fitted where we were at the time. if you have something that you really, really desire, and you’re good at it ... don’t let anybody deter you from it."

Along with Gloria Gaynor’s “I Will Survive,” “We Are Family” is the most enduring empowerment anthem of the disco era. Rodgers named his global nonprofit charity the We Are Family Foundation, and it earned Sister Sledge a hometown gig opening for Pope Francis on the Benjamin Franklin Parkway in Philadelphia at the 2015 World Meeting of Families.

That performance was without Kathy Sledge, who left the group in 1989. In 2014, Joni, Debbie, and Kim sued their youngest sister, claiming she was not authorized to use the Sister Sledge name, and the suit was settled out of court.

Ms. Sledge’s death was mourned by fans on social media over the weekend. Ahmir “Questlove” Thompson of Philadelphia’s the Roots wrote on Instagram:  “More than just the pride of Philadelphia, or my first musical crushes, Sister Sledge meant the world to me.”

On Saturday, the Sledge family released a statement: “Yesterday, numbness fell upon our family. Pray for us as we weep for the loss of our sister, mother, aunt, niece and cousin Joni Sledge. We thank you for privacy as we hurt for her presence, but also for embracing her radiance and the sincerity with which she loved life.”

Joni Sledge is survived by her son, Thaddeus, and her three sisters. Funeral services have not yet been announced.