“She had the best eye for photography,” said Mr. Lindbergh, who began working with Ms. Sozzani in the early 1980s and kept up their collaboration for so long that Ms. Sozzani referred to herself as “the longest wife in your life.” (They were not, in fact, married, though Mr. Lindbergh did say in a phone interview, only partly in jest, that he had been in love with her.)
“Italian Vogue was the most inspiring Vogue in the world,” he added. “For over 25 years, Italian Vogue was ahead.”
Born in Mantua, in the north of Italy, Ms. Sozzani found herself in fashion as if by accident. After floundering in high style — she took a university degree in philosophy, entered into a brief marriage (annulled after three months) and made soul-searching visits to India and London — she returned to Italy and wound up an “assistant to the assistant to the assistant to the assistant” of Vogue Bambini, a children’s clothing magazine.
She was named editor of Lei in 1980, where she began to work with the photographers with whom she is still associated, adding its men’s counterpart, Per Lui, in 1982 before taking over Italian Vogue in 1988.
Though she was a beauty, with Pre-Raphaelite curls and a durable elegance immune to trends, she was not entirely seduced by the world of appearances in which she traveled.
“Here’s what I think: Fashion isn’t really about clothes,” she said in an interview in 2013. “It’s about life.”
Accordingly, her magazine — though it showed clothes, and plenty of them — never shied from the reality in which her readers lived. Her irreverence could border on the heretical. In one famous shoot by Mr. Meisel, on the theme of plastic surgery, she showed doctors hard at work on Linda Evangelista and a host of other models who were being injected, tucked and generally remodeled while blithely chatting away on their cellphones and then recovering at the St. Regis.
But she addressed herself to serious concerns, too, dedicating photo shoots and special issues to themes too delicate for her international colleagues to touch: drug abuse and rehabilitation; domestic violence; the Gulf oil spill of 2010.
Italian Vogue’s “black” issue, in July 2008, when Americans were considering electing their first black president, was a controversial best seller, featuring models of color exclusively.
Ms. Sozzani’s approach “gave Vogue a kind of power and surprise,” Mr. Newhouse said in an interview. There are two ways to make a magazine, he went on. “One path is a conventional path,” he said, “to fulfill what’s expected, always give the readers and the advertisers what they want, and do it in the best way. That’s a way that works.
“Another way is to break the mold and surprise and provoke and sometimes disturb your readers. That’s a much harder way to do it, and it’s much harder to do well, and Franca did it better than anybody.”
Her fellow provocateurs applauded her for it. “It’s all about Italian Vogue,” Madonna said in an interview with Aperture magazine in 1999. Or as Fabien Baron, the art director who worked for Ms. Sozzani at Italian Vogue, put it to Newsweek, “If Anna Wintour is the Steven Spielberg of fashion magazines, Franca is Pedro Almodóvar.”
Such risks did not endear her to every reader, and Ms. Sozzani’s choices — and her remarkably forthright blog on Italian Vogue’s website — could raise hackles. Some objected to her shepherding black models into a “special” issue; others disliked the oil-spill photographs, calling their portrayal of the model Kristen McMenamy as a sort of high-fashion, oil-slicked bird of paradise insensitive.
“When you take risks, it means that you know every month, people are there to judge you,” Ms. Sozzani told Interview magazine in 2012. “Some months are good; some months are bad. When you make a mistake, they call you immediately. And when you do something good, they send flowers to the stylist.”
Ms. Sozzani took special care to nurture emerging designers with Vogue’s Who Is On Next? Prize. “She was a godmother to talent everywhere,” Diane von Furstenberg said in an interview.
But she was also attuned to the issues of the world outside fashion. In 2012, the United Nations named her a good-will ambassador of the fashion industry advocacy group Fashion 4 Development, working to encourage sustainable development in Africa. In 2014, she was made a global ambassador against hunger to the United Nations’ World Food Program.
Ms. Sozzani had a son, Francesco Carrozzini, whom she raised more or less alone. Mr. Carrozzini, a photographer and filmmaker, made a documentary about her, “Franca: Chaos and Creation,” which had its premiere at the Venice Film Festival September.
“My mother sacrificed herself for me and for her work,” Mr. Carrozzini told The New York Times. “Her love life was the price she paid.”
Still, she was known as a social connector nonpareil. She collected work by Andy Warhol and Barbara Kruger, hosted dinners attended by Jeff Koons and V. S. Naipaul, sailed the Mediterranean with business leaders like Barry Diller, and helped designers like Donatella Versace get back on their feet when they wound up in rehab.
For Ms. Sozzani, fashion was a family business. Besides Mr. Carrozzini, who often shot for Italian Vogue and its brother magazine, L’Uomo Vogue, she is survived by her sister, Carla Sozzani, the owner of a pathbreaking chain of boutiques, 10 Corso Como, and a niece, Sara Maino, an editor at Italian Vogue.
“We lose a person who gave everything to Italian fashion,” the designer Miuccia Prada and her husband, Patrizio Bertelli, the chief executive of Prada, said in a statement. “Our love for Franca surpasses friendship after having worked together for our entire life.”
Ms. Wintour, the artistic director of Condé Nast and the editor of Vogue, posted a remembrance on Vogue.com, describing Ms. Sozzani as “warm, clever, funny, and someone who could give the Sphinx a run for its money when it comes to keeping a confidence.”
“I will never forget the energy of that woman,” said Federico Marchetti, the chief executive of Yoox Net-a-Porter Group, which works with Italian Vogue on the Who Is On Next? project. “Throughout her life and career, including to the end of her life, she continued to do everything.”
The fashion stylist Lori Goldstein credited Ms. Sozzani with kick-starting her career.
“Artists and talent flowed to her, and it wasn’t because she was Italian Vogue but because Italian Vogue was her,” Ms. Goldstein said in another interview. “Everywhere else, there were tons of rules. Fashion became a total noncreative business with all these people who try so hard. Franca didn’t have to try. She wasn’t trying to be cool. She wasn’t trying to be revolutionary. She just was.”