In January, Kate White, the editor of Cosmopolitan magazine, went to David Carey, the president of Hearst Magazines, and told him she was thinking about retiring after 14 years on the job. Given the importance of the franchise to the company, Carey immediately set about looking for a successor both inside and outside of Hearst.

He found the answer just two floors away: Joanna Coles, the editor of Hearst's Marie Claire magazine.

In six years guiding Marie Claire, the British-born Coles has improved the visibility of the magazine - once viewed as an also-ran - by taking it upscale and into some rarefied fashion realms. Her profile has risen along with the magazine's, with a growing reputation at fashion shows and a regular position as one of the judges on "Project Runway All Stars."

The appointment installs new leadership at an iconic publication that has evolved from a general interest and literary magazine to an aspirational companion for young women, covering fashion, relationships and, more recently, careers - all with a heavy dose of sexual candor. It was largely transformed in the 1960s when Helen Gurley Brown, who died last month, remade it by latching on to feminism and the sexual revolution.

Since then, it has remained a stalwart of the Hearst brand, managing to gain in circulation in recent years at a time of extreme financial challenges for the magazine business.

Given the youthful audience of Cosmopolitan and the ubiquity of fashion and relationship guidance on the Web, making sure that Cosmo excels in digital realms is a high priority at Hearst.

Coles said she welcomed that challenge. Sitting in the 42nd-floor offices, dressed in purple, geometric Prada pants, a black English top and black Givenchy heels , said she can't wait to get her hands on Cosmo.

"I'm incredibly excited about the global footprint ," said Coles. "It's big because it talks about things that are really important to women. It's such an iconic logo."

There are probably more prestigious magazine franchises to edit, but few have the traction and heft of Cosmo, which advocates a "fun, fearless " approach for young women as if it were the secret to all of life's important questions. White has worked to modernize Cosmo to fit the times and account for the progress women have made in the business world.

"Cosmo readers are very eager for anything about careers, in part because it is so competitive out there," said White, an author of eight mystery and thriller novels who is finishing up her fourth work of nonfiction, "I Shouldn't Be Telling You This," an advice book. "Young women have a lot more choices now than they used to and they are anxious about making the right ones."

White, 61, will remain at Hearst until the end of the year working on some projects with Carey, but said that she has been itching to spend more time on her books - "I'm looking forward to working just 55 hours a week" she said - and also create a bigger presence on social media in support of her literary work.

The baton White is handing off is in pretty good shape. Even in a struggling magazine industry where most titles are losing subscribers in droves , Cosmo's circulation has risen steadily over the past four years and peaked in the first half of 2012 with 3,017,834 subscribers, according the Audit Bureau of Circulations. Glamour, a competitor owned by Conde Nast, has a circulation of 2.37 million.

Cosmo's appeal transcends American borders: There are 64 international editions, including Slovenia, Ecuador, and China. The magazine also has kept up with its subscribers as they have moved over to digital media. While digital subscriptions often make up 1 to 2 percent of total magazine readership, Cosmo now has 137,000 paid digital subscribers. It said it attracts 8.5 million unique visitors to its website a month. Its 349,156 followers on Twitter and 1.8 million "likes" on Facebook get a steady flow of shopping discounts mixed in with advice like how the right music can make you eat less and 10 tips on surmounting a break up .

Cosmo is built on mixing the practical with the fatuous. An article by the comedian Andy Samberg in the September issue includes "7 Signs He Isn't Relationship-Ready," which advises readers to stay away from men who live with their mothers, are married or are VIPs at a strip club - unless the reader is a stripper.

Coles is a former reporter - who are not necessarily prized for their fashion sense - and has worked for both The Guardian and The Times of London. She first worked at New York magazine when she came to the United States and then became editor of More, a magazine aimed at women over 40, and now finds herself editing a magazine for women who think middle age is some ancient, distant planet they may travel to one day.

Coles said she wants the often- puzzling journey through one's 20s and 30s to be as fun for readers as it was for her. She said she bought her first apartment at 23 as she began working her way up in the male dominated world of newspapers.

She pointed to the frank talk about sex and careers on shows like HBO's "Girls" and "Two Broke Girls" as an indication that the rest of the culture shares the concerns of Cosmo readers.

"The 20s and 30s are incredibly exciting and full of potential, but also a little overwhelming," Coles said. "The things that keep women awake now are the same things that kept women awake 30 years ago."

Coles said that when she arrived at Marie Claire she was surprised at how negative many women's magazines were. She said it underscored to her how important it is that Cosmopolitan makes women feel better about themselves.

"For me what's important is to be on the side of women when it comes to sex," she said, and then added, "It's very important to have a sense of humor when you edit a magazine. I have a lot of learning to do. There are 365 sex positions of the day here and one of them is called the linguine."