Mary Norris is concerned about the future of the apostrophe. In a time when abbreviations and emoticons take on the roles of fully expressed words or emotions, the apostrophe could be in jeopardy.

“The apostrophe is most vulnerable to the march of progress,” said Ms. Norris, a query proofreader for The New Yorker since 1993. She began working at the magazine in 1978.

“The apostrophe isn’t really punctuation, it’s spelling,” she explained while sitting in Battery Park on a recent summer morning, not too far from her office at One World Trade in downtown New York city.

Take Martha’s Vineyard for example. The apostrophe was eliminated for almost 40 years before it was restored in 1933. The Island, after all, is named after explorer Bartholomew Gosnold’s daughter Martha.

“Martha’s Vineyard really is a case in point,” the author said. “It’s historic. Spelling is historical. It tells you more about the word than you would learn if it were spelled phonetically and without an apostrophe.”

But as long as The New Yorker is being published, Ms. Norris said, the storied magazine will “certainly be employing the apostrophe.”

She began working at The New Yorker in the editorial library and now as one of the lead copy editors, she ensures that commas and diereses are properly placed. She uses No. 1 soft lead pencils, has a special fondness for dictionaries and tries not to correct people in public because it only makes enemies.

On Saturday, Ms. Norris joins a panel of fellow memoirists at the book festival to discuss her new book Between You & Me: Confessions of a Comma Queen. She also appears on Sunday for an interview with George Gibson, publishing director of Bloomsbury USA.

The book provides grammar lessons through parables, stories about eccentric employees at The New Yorker and personal anecdotes.

Ms. Norris always wanted to be a writer. “I don’t know anyone who sets out in life to become a copy editor,” she said. When she was just starting out she met Peter and Jeanne Fleischmann through her brother. Mr. Fleischmann was chairman of the board at The New Yorker at the time, and his father Raoul was founder of the magazine. They took Ms. Norris under their wing and became surrogate parents, and one hefty phone call later, she landed a job in the editorial library of the magazine.

“From there I began to see what kinds of jobs there were in a magazine,” she said. “The one that I focused on that I thought I could do was copy editing.”

All the while, Ms. Norris kept writing.

“I thought a foot in the door might help, and it didn’t hurt, but it didn’t help that much either,” she said with a laugh. Ms. Norris kept at her writing, publishing pieces here and there, hoping for her big break. But it didn’t come until 2012 when Ben Yagoda published a piece in The New York Times criticizing the zealous use of commas at The New Yorker.

Someone had to defend the stylebook.

“I was not all that excited to write about commas but I thought I should have some team spirit if he made fun of The New Yorker,” Ms. Norris said. So she wrote In Defense of Nutty Commas for the magazine. It was a hit.

“And on such a dull subject!” she exclaimed.

She continued to write about the quirks of The New Yorker style, and a book idea was born. Topics include spelling, when to use “that” versus “which,” dashes, semicolons and colons, profanity, and her biggest pet peeve of grammatical inaccuracies: between you and me.

“It’s that use of I when it should be me,” she said, wrinkling her nose. “It’s one of the things I really am evangelical about. That’s a mistake that educated people make and it’s a mistake people make when they’re trying to sound educated. The trick is just to put I first. No one would say between I and you. Between me and you? Yeah.”

She plans to leave signed a copy of her book for President Obama, an offender of the phrase, when he visits the Vineyard for his August vacation.

“Michelle does it right, she’s got confidence,” she observed. “I don’t think he would say between you and I but he will often say something like, thank you very much for throwing this dinner for Michelle and I. He’s just being deferent and using it as a unit and I know that descriptive grammarians think it’s fine. But I don’t agree.”

American language is always in flux but especially now, Ms. Norris said, in a world of self-publishing, social media and blogs.

“The need for editors is really strong,” she said. “It’s fine with me that people express themselves in any way they want, they’re just trying to communicate. If people want something read in a public way, I think editors are important.”