As it turns out, you can eat lunch in this town (or teach history lessons) even after writing a tell-all book.

Just ask Andrew Trees, the Horace Mann high school teacher whose New York prep school novel, “Academy X,” was published in June by Bloomsbury. Despite having detailed the moral pliability of the well-heeled families who send their children to the city’s elite private schools, Mr. Trees, 37, returned this fall to his teaching post at, well, one of the city’s elite private schools.

The fictional Academy X — full of spoiled students, uninspired teachers, and spineless administrators — is not a thinly veiled Horace Mann, Mr. Trees said. “The kind of stuff I wrote about goes on all over the place,” he said. “I was writing about a general problem. The book was never meant to be a portrait or an indictment of the school.”

In fact, he said, “people at the school are pretty sophisticated, and they realize it’s a novel. I don’t think anyone takes it personally.”

Earlier this year, Mr. Trees worried that “Academy X” would spell the end of his career at Horace Mann, where he teaches ninth-, 11th-, and 12th-grade history. He had good reason to fear for his job: His portrait of a city prep school as “an ethical wonderland in which up is down, and right is wrong” is anything but flattering. Yet Mr. Trees is still there and says he is gratified by the overwhelmingly positive response of his students and colleagues. “It’s an academic institution,” he said. “I think people have a fair amount of respect for people who publish books.”

Employees at the Riverdale school do not sign a confidentiality agreement, though there is an implicit understanding that teachers shouldn’t divulge most details of students’ private lives, the author said.

A parent of a child at the school, Edward Zuckerberg, said he supports Horace Mann’s decision to allow Mr. Trees to keep his job. “As far as the school taking him back, that should be based on his merits as a professor,” he said.

Even so, Dr. Zuckerberg, whose daughter, Arielle, is a senior, said he couldn’t imagine that Mr. Trees was welcomed back warmly, given the airing of dirty laundry he did in the book. “If it’s based on truth, even if it’s stretching it, it’s probably fair game but it isn’t cool,” Dr. Zuckerberg, who has heard about the book but has not read it, said. “I wouldn’t want to be the teacher going back to the school after that. Anytime you’re dealing with comments about other people that probably should remain private, you’re subject to eliciting hard feelings.”

“What did he do this time?” a woman answering phones at the school replied when asked about Mr. Trees.

The head of the upper school, Barbara Tischler, said she would not comment about Mr. Trees or his book. Calls to Horace Mann’s former head of school, Eileen Mullady, were not returned. Ms. Mullady, who some suspect was the inspiration for the book’s maligned head of school, last year left her job to lead a prep school in Southern California.

A 17-year-old senior at Columbia Preparatory School on the Upper West Side, Cara Gerstle, said she understands the public fascination with “Academy X.”

“It’s a world that a lot of people don’t have an opportunity to travel into,” she said. “It’s a fantasy world. There’s a curiosity among people who want the inside scoop.”

Still, she said Mr. Trees’s decision to write the book was “tacky” and “disrespectful,” and that she hoped her school would fire any teacher who used the job as fodder for a juicy novel or memoir. “In the classroom, there’s a student-teacher bond that’s established,” she said. “Once that trust is broken, you can’t have a successful bond.”

These days, spilling workplace secrets in print doesn’t always secure writer’s a place on a blacklist. For the authors of “The Devil Wears Prada” and “The Nanny Diaries,” for example, dishing led to additional book contracts, mega-paychecks, and movie deals. “People wildly overestimate the risks associated with writing a tell-all book,” Toby Young, who wrote about his unsuccessful stint working for Vanity Fair in a 2003 book, said. ” Before I published ‘How to Lose Friends & Alienate People’ my career was in the toilet, whereas now, well, it’s still in the toilet to tell the truth, but at least I’ve carved out a niche for myself as a professional failure.”

Apparently, he has. His follow-up memoir, “The Sound of No Hands Clapping” was published recently by Da Capo in America and Britain.

Mr. Trees said he wants continue teaching, even as he pursues a literary career. He’s at work on a second novel, of which he would only say: “It deals with some of the same excesses in New York society.”