What started as a scandal became a classic. The song was later sampled by LL Cool J, Timbaland and Beyonce, who interpolated the hit for her jam "Naughty Girl." It was also Summer's U.S. chart debut and the first of 19 No. 1 dance hits between 1975 and 2008 — second only to Madonna.
Summer, real name LaDonna Adrian Gaines, was born in 1948 in Boston. She was raised on gospel music and became the soloist in her church choir by age 10.
"There was no question I would be a singer, I just always knew. I had credit in my neighborhood, people would lend me money and tell me to pay it back when I got famous," Summer said in a 1989 interview with The Associated Press.
Before disco, she had already reinvented herself several times. She sang Motown songs with local groups in Boston as a teenager, then dropped out of school in the late 1960s and switched to pyschedelic rock after hearing Janis Joplin. An attempt to get a part in the musical "Hair" led her to get the principal role in Munich. She stayed in Germany for five years, worked in other productions and modeled.
Meanwhile, she was performing in operas, singing backup for Three Dog Night and other groups and releasing songs of her own. A marriage to Helmuth Sommer didn't last, but the singer did hold on to her ex-husband's last name, changing it to "Summer." By 1974, she had met producers Giorgio Moroder and Pete Bellotte and released her first album, "Lady of the Night," to success in Europe.
Then came "Love to Love You Baby," her memorable U.S. debut. Through the rest of the disco era she burned up the charts: She was the only artist to have three consecutive double-LPs hit No. 1, "Live and More," ''Bad Girls" and "On the Radio." She was also the first female artist with four No. 1 singles in a 13-month period, according to the Rock Hall of Fame, where she was a nominee this year but was passed over.
Musically, she began to change in 1979 with "Hot Stuff," which had a tough, rock 'n' roll beat. Her diverse sound helped her earn Grammy Awards in the dance, rock, R&B and inspirational categories.
Summer said grew up on rock 'n' roll and later covered the Bruce Springsteen song "Protection."
"I like the Moody Blues, the Beatles and the Rolling Stones as well as Aretha Franklin, Dionne Warwick, the Supremes and Temptations," she said. "I didn't know many white kids who didn't know the Supremes; I don't know many black kids who don't know the Moody Blues."
Warwick said in a statement that she was sad to lose a great performer and "dear friend."
"My heart goes out to her husband and her children," Warwick said. "Prayers will be said to keep them strong."
Summer later became a born-again Christian and was accused of making anti-gay comments in relation to the AIDS epidemic — a particular problem for a woman who was and remains a gay icon. Summer denied making the comments, but became the target of a boycott.
Religion played an important role in her later life, said Michael Levine, who briefly worked as her publicist.
"Her passion in her life, besides music, was God, spirituality and religion. She held a bible study class at her home every week," he said.
Summer released her last album, "Crayons," in 2008. It was her first full studio album in 17 years. She also performed on "American Idol" that year with its top female contestants.
Summer is survived by her husband, Bruce Sudano, and three daughters, Brooklyn, Mimi and Amanda.
AP National Writer Hillel Italie in New York and AP Music Writer Nekesa Moody and Entertainment Writer Sandy Cohen in Los Angeles contributed to this report.
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