ONDON, Dec. 16 ≈ The novelist Zadie Smith was on a busy street here not so long ago when she spied the face of fame, circa 2002. Walking in the other direction was the winner of the latest series of "Big Brother," a once-unknown woman who had, by a sequence of small random exertions, been transformed into one of Britain's most instantly recognizable celebrities.

But the crowd on the street, presumably made up of the sort of people who had watched the show and purchased the magazines stuffed with "Big Brother"-related gossip, was anything but impressed. "People were laughing at her all the way down the street," Ms. Smith related recently. "She had obviously been crying ≈ she had mascara all down her face ≈ and they were pointing and jeering. She looked so embarrassed to exist."

Ms. Smith, 27, whose ecstatically received first novel, "White Teeth," bestowed upon her a different but perhaps just as tricky brand of fame, has been thinking a lot about celebrity: its hold on the culture, its cruelties, its triviality. Interviewed over coffee and cheesecake in a cafe here, where she was taking a break from a writing fellowship at Harvard, she seemed at once more guarded and more relaxed than she had two and a half years ago, in the throes of sudden acclaim after the publication of her best-selling first book.

That was "White Teeth," a sprawling, generous stew of a story set in modern multicultural London and widely acclaimed as one of the most original first novels in years. Full of the author's exuberant style and elegantly funny touches, Ms. Smith's second book, "The Autograph Man," published this fall, is altogether different, a deliberate effort on her part, she said, to produce something tighter, more focused.

"The Autograph Man," the story of a professional autograph trader unable to come to terms with the death of his father, and searching for a rare autograph from a reclusive aging movie star, has had mixed reviews, ranging from very good to very bad.

"This is, in the end, a touching, thoughtful, deeply felt rite-of-passage novel," wrote Anne Chisholm in The Sunday Telegraph. In The New York Times Book Review, however, Daniel Zalewski, an editor at The Times Magazine, said, " `The Autograph Man' is more entertaining than lots of novels, but it doesn't come close to the divine mess of `White Teeth.' "

Ms. Smith is not sure whether she particularly minds, although she admits to feeling indifferent to the positive reviews and unhealthily obsessed by the poor ones. Like other writers of her generation, including Jonathan Franzen and Dave Eggers, she is self-consciously familiar with the literary landscape and with the strains that come with being suddenly acclaimed as the New New Thing.

"Everything in the culture is so hysterical," she said. Her hair tied back with a bright pink scarf, she was suffering from a head cold and spoke in a sexy rasp. "Everything is fantastic, or it's the worst thing; you should either be given a Nobel Prize or shot at dawn."

After "White Teeth," for instance, she found herself being deluged by offers to appear on television, to write for the newspapers, to be photographed for magazines. She recently rejected as ludicrous a chance to be on the cover of Time Out, a weekly entertainment magazine in London. No yearning for a "Big Brother"-esque experience for her.

"It was a ridiculous request," she said. "I've never been spotted on an English street in my life, and I don't expect it ever to happen." Of fame in the literary world, she said: "It's irrelevant to the greater portion of people. But that's one of the greatest things about writing. Unless you're Norman Mailer, it's a fairly anonymous profession."

Still, it has been hard for Ms. Smith ≈ striking in appearance, clever of tongue and young and influential enough to be proclaimed one of the voices of her generation ≈ to remain completely anonymous, at least in the gossipy world of literary London. This fall several newspapers, most notably The Evening Standard, printed articles full of anonymous quotations and shady innuendoes about her college relationships, her writerly ambitions and her London background. She is an intriguing target, both because of her success and because she has tried so hard to keep her personal life, including details about her longtime boyfriend, private.

It is no wonder, then, that she has temporarily left Britain to take up her fellowship at Harvard. There she is working on a book of essays about the novel as a moral form that she hopes, she says, will be a defense of "the idea of the book as a suitable place for ethical inquiry." Her first chapter is on E. M. Forster, one of the writers she most admires.

She does not think "The Autograph Man" is a great novel, she said, in part because of the trickiness of its topic. "The actual subject of fame is so fatuous," she said. "I thought I'd try to deal with it instead of pretending it didn't exist, but maybe it can't be touched without an equal amount of fatuousness coming into the writing."

The book is also a meditation on Jewishness (its protagonist, Alex-Li Tandem, is the product of a Jewish father and a Chinese mother) and a moving examination of how a return to faith can help calm a troubled soul.

"I wrote the book reading a lot of Kafka," Ms. Smith explained. "The idea was that it was meant to be a commentary on the Zohar, the way the Zohar is a commentary on the Talmud."

Her voice trailed off, and she laughed. "The most painful thing in the world is an author explaining their own novel," she said. "If those things aren't clear, then that is my fault."

These are tough words. But then, Zadie Smith has always seemed fully prepared to be her own harshest critic, famously dismissing "White Teeth" as "the literary equivalent of a hyperactive, ginger-haired tap-dancing 10-year-old."

"If I ever criticize `White Teeth,' it's not because I don't think it's an enjoyable book," she said. "But sometimes things can be almost too enjoyable. Sometimes they can be morally light about the way life proceeds.

"I couldn't write `White Teeth' again anyway; there's a six-year gap, and I feel a million miles away. But I love `The Autograph Man' for its sadness."

She wrote it when her father was very ill and she was consumed by thoughts of death. "People my age fail to deal with it, and the culture fails to help them deal with it," Ms. Smith said. "It pretends death doesn't exist, until suddenly you're in a National Health Service hospital about to keel over and someone tells you, `Oh, by the way, along with MTV and shopping, there's death.' "

The book is full of a kind of playfulness. Like the works of Mr. Eggers, a friend of Ms. Smith's, it has its share of charts, jokes and explanatory pictures. "It's a common thing with our generation, but I want to show you the things that I love," Ms. Smith said. "I probably should keep them to myself, but I find them funny and they're intimate to me."

She is in no hurry to produce her next novel, she said, although she has not abandoned fiction. But she seems remarkably unconcerned about the demands of the literary marketplace and will not admit to working on anything new.

"I find it very odd that if I was sitting around toying with four paragraphs, I could say, `Yes, I've started some new fiction,' " she said. "It would become an economic entity and a real thing in the world, whereas before it would have just been, `Zadie's just scored a few paragraphs.' I find it all very unnerving."

Several of the negative reviews accused Ms. Smith of being derivative, but she does not mind. While she was working on the book, she said, she was reading a lot of Kafka, Nabokov, Martin Amis, and she did not try to shake them off.

"I'm influenced by everything I read, shamelessly," she said. "In a review someone said, `Oh, she sounds very much like Amis.' I was flattered by that. I love Amis. Thank you very much. I think if I carry on plagiarizing for 15 years, it will settle like silt, and I'll write something really great."