Edith Raymond Locke, who fled Nazi-occupied Vienna at 18 and rose to become a longtime editor of Mademoiselle magazine, where she worked with photographers like Arthur Elgort and mentored designers like Ralph Lauren, Betsey Johnson and Donna Karan, died on Aug. 23 at her home in Thousand Oaks, Calif. She was 99.

Her daughter, Katie Aviv, confirmed the death.

In the youthquake 1960s and beyond, Ms. Locke was a booster of young designers, models and photographers.

One talent was Ms. Johnson, who, after being a guest editor in 1964, stayed on at the magazine’s art department and made silver lamé T-shirts and skinny sweaters she sold to her colleagues. Impressed by her exuberant style, Ms. Locke recommended Ms. Johnson to Paul Young, the British entrepreneur who ran Paraphernalia, an influential youthquake emporium, making Ms. Johnson’s career.

Ms. Johnson called Ms. Locke “my fashion mommy” in a 1995 interview with The New York Times.

Another was Donna Karan, who was an assistant at Anne Klein in the late ’60s when Ms. Locke encouraged her to take the top job there after Ms. Klein’s death in 1974. “She was my ‘look up to,’ but in a caring, loving way,” Ms. Karan said. “She made the fashion industry feel real. I was very intimidated, as the assistant to the assistant to the assistant. I felt a warmth from her that carried through till the last time I saw her. It wasn’t by season, it was by lifetime.”

And she was an early champion of Mr. Lauren, who said that Ms. Locke continued to attend his fashion shows well into her 80s. “When I started out, Edie and her cool fashion team at Mademoiselle got what I was doing,” Mr. Lauren said in an email. “We shared the same vision about fashion. It wasn’t about what’s new or what’s next, but what lasts. Edie lasted.”

Edith Rosenberg Laub was born Aug. 3, 1921, in Vienna. Her father, Herman, was a buyer for a department store; her mother Dora (Hochberg) Laub, was a homemaker. A younger brother died in infancy.

Edith was a popular, bright student, a favorite of her school’s principal, for whom she would memorize pages of Goethe to recite. She tutored her classmates in Latin, math and German. But after the Nazis marched into Vienna in March 1938, Edith and the other Jewish students were ejected from the school. Her friends announced they would no longer speak to her.

Herman was fired from his job. Nazis appeared at their apartment door to rifle through their belongings (at one point confiscating German translations of Sinclair Lewis and Upton Sinclair as “communist literature”) or to force Edith and her mother to perform pointless, humiliating tasks, like washing the floor of a Nazi Party office.

Credit…via Katie Aviv

In April 1939 Edith left Vienna for New York City, arriving on the British ocean liner Aquitania. She was 18, spoke no English and was alone. Her parents were unable to get visas to America, which maintained strict quotas for European immigrants, and they would spend the war years in England.

She lived with relatives in Brooklyn; worked in a toothpaste factory, among other jobs; and learned English at night school. A secretarial job at Harper’s Bazaar led to an assistant editor position at Junior Bazaar, a competitor to Mademoiselle.

She also worked at the Abbott Kimball Company, an advertising agency, where she wrote a regular newsletter about fashion. It was sharp enough to catch the attention of Betsy Blackwell, the editor in chief at Mademoiselle, who hired her in the early 1950s.

Mademoiselle, or Millie as it was nicknamed, was devoted to fashion and beauty but also literature, publishing the work of James Baldwin, William Faulkner, Jane Bowles, Truman Capote and Carson McCullers, among many other authors.

It was known, too, for its guest editor competition, when college juniors were invited to edit the magazine’s August issue, and were put up at the Barbizon Hotel. (Sylvia Plath was chosen in 1952, and rendered her darkening summer there in “The Bell Jar.”)

As a fashion editor, Ms. Locke set photo shoots in exotic locales, working with tourist offices who were eager to attract Americans. She photographed models in the Canary Islands (one, memorably, on a pregnant camel), Corsica, Sicily, Greece and, much later, the Caribbean, where she met her husband, Ralph Locke, a travel agent who was managing the Buccaneer, a resort in St. Croix.

Credit…H. Landshoff
Credit…H. Landshoff

Ms. Locke became editor of Mademoiselle in 1971, when Ms. Blackwell retired. It was still a time when fashion editors wielded enormous influence. The eccentric and hortatory Diane Vreeland had just been fired from Vogue, yet her persona was much imitated. By all accounts, Ms. Locke was, by contrast, more cheerleader than dictator. She let her editors have their heads.

In the memoir she was working on at the time of her death, she wrote of her long struggle to keep the magazine’s intellectual heft and “smart girl” DNA.

One of her first issues as editor was devoted to female sexuality, with contributions from Henry Miller, Germaine Greer and John Updike. “Hooray for you,” wrote one delighted reader in response.

Alexander Liberman, editorial director of Condé Nast, was unmoved. He found “Mlle’s features “depressing and heavy,” she wrote, and wanted a “lighter and sexier” magazine. In 1979, he ordered Ms. Locke to kill the guest editor program, and he fired her the following year. (Mademoiselle ceased publication in 2001.)

In 2016, Ms Locke told an interviewer that what she loved most about working at Mademoiselle was “making it more inclusive, by diligently balancing content between fashion-beauty, how-to features, and intellectually stimulating articles. Feeding the brain!”

After Mademoiselle, she produced and hosted a women’s cable television show called “YOU! Magazine” for the USA Network. In 1985, she co-hosted a fashion segment for “Attitudes,” a lifestyle show on Lifetime that featured nearly every major American designer during the early 1990s.

In 1994, Ms. Locke and her husband moved to Los Angeles to be near their daughter. They survive her, along with three grandchildren.

Credit…Katie Aviv

“Her big phrase was carpe diem,” Ms. Aviv said. “That was her sign-off, every email, every note or phone call.” She wore a silver bangle inscribed with those words, and gave them to dear friends like the actress Ali MacGraw (a Mademoiselle guest editor in 1959).

“She was completely present, with studied opinions, compassionate,” Ms. MacGraw said in a phone interview. “Her values were superb and rare in the fashion business, where there’s a tendency to drink the Kool-Aid and lose track of reality. She loved the business, and she succeeded in it without losing the whole human being that she was.”