Lee Fiora, the protagonist of Curtis Sittenfeld’s first novel, “Prep,” learns no major life lessons in her four years boarding at the Ault School, an exclusive, Grotonesque institution. She doesn’t encounter any inspirational teachers in the “Dead Poets Society” vein to show her how one person can make the cold, cruel world a warmer place. There are no Christ figures, students finding “A Separate Peace,” sacrificing themselves for everyone else’s sins. And she doesn’t sit around musing about man’s inhumanity toward man, or where the ducks go when the lake freezes over; she’s too busy trying to calibrate the exact moment her crush is going to walk through the dining hall, so that she can brush past him closely enough so that he’ll notice her, without actually having to think up something to say.

Reading the book, I was reminded of a truth that I had forgotten: Youth isn’t wasted on the young; it’s endured by the young. America has been celebrating youth culture since the concept of the “teenager” was invented during World War II. But never before have so many adults been so fascinated by teenagers as we are today. Once, teenage celebrities were ghettoized into the pages of teen magazines (a moment which turned out to be a career pinnacle for so many – poor Scott Baio!). Now teenie actresses like Lindsay Lohan grace the covers of mainstream magazines from the salacious (nude on the cover of Entertainment Weekly) to the supermarket tabloid (she’s a Star favorite).

The break-up of Mary-Kate and Ashley Olson, the 18-year-old twin child stars and NYU students who are now moving into separate apartments, has caused only slightly less ink to be spilled than the separation of Brad Pitt and Jennifer Aniston. And “American Idol” just upped the maximum age of its contestants to 28 because really, if you haven’t made it as a major media sensation by the age of 28, you never will. A mediocre voice is one thing; a mediocre voice in a 30-year-old seems to be a freak show akin to “Whatever Happened to Baby Jane?”; normal people will simply want to look away in horror.

To glance at the magazine aisle, it seems teenagers have never been so empowered, rich, and confident. (Or such eager consumers; most women’s magazines now have mini-me versions – Elle Girl and Teen Vogue.) Broaden your gaze to take in the rest of the Duane Reade and you’ll see teenagers dressed like adults (or at least exotic dancers, which is another form of adult) and grown-ups struggling to fit into low-waisted jeans designed for flat, pre-pubescent stomachs. It’s enough to make my 30-year-old self wonder what I was doing all those years, wasting my youth when I should have been writing erotic diaries a la Italian literary sensation Melissa Panarello, or working on my singing career. (Lack of material for the teenage erotica and the lack of vocal talent are no excuse; one sex tape and some canny handlers could have solved my problems.)

When teenagers seem as stylish, sassy, and savvy as the more mature women of “Sex and the City” (television women in their 30s and 40s are no longer sexy singles but “Desperate Housewives”), it’s easy to yearn for a time when your tummy was taut, your heart whole, your soul unspoiled, when you were a teenager and the world was yours to discover. “Prep” (Random House, 416 pages, $21.95), an engaging if meandering novel, serves as brilliant correction to that yearning. It is an unflinching look at how even high school experiences that are perfectly fine – no abuse, incest, pulling the family up out of homelessness – can feel like four years in Purgatory.

It’s not that Lee is bored by the Ault School; it’s that she’s obsessed by it. With no other life experience to draw on, the high schooler feels high school is the world. Lee is so entrenched in the school’s culture – when it’s appropriate to show enthusiasm (at a sporting event) and when it’s not (everyplace else) – that when she takes the subway after graduation and looks around to see nurses, grandmothers, a man in a suit, she thinks, “All these people … What had they been doing for the last four years? Their lives had nothing to do with Ault.”

A scholarship student, Lee spends her life at Ault as an outsider, struggling to reassure herself that she’s not one of pitied freaks but convinced that she is not rich or pretty enough to be part of the cool crowd, girls with names like Horton and Aspeth. (With a name like Curtis, and sisters named Tiernan and Josephine, I’m tempted to imagine that the author of this novel, according to the rules of naming established in the book, was not a scholarship student.) Lee’s passivity annoys her best friend, her crush, even her teachers, one of whom gives her an F for an assignment to write an essay “on something that mattered to us,” a paper on which Lee adds the caveat, “This is not an issue I truly care about, but I believe it fulfills the assignment.”

Lee may be an extreme example of passivity, but the achievement of “Prep” is to remind the reader that even the most dynamic of Lee’s classmates feel that life is happening to them, not for them, as they wait to see whether they’ll be elected Senior Prefect, whether the boy they like will send them a flower on Valentine’s Day, whether they’ll get into the college of their choice. Life continues to be filled with uncertainty after high school, but having survived that experience most of us know that whatever the outcome of a situation, we have the power to react, to change our lives. Adults leave jobs they hate, find new lovers, dye their hair after a big breakup. If your husband doesn’t send you flowers on Valentine’s Day, chances are the disappointment won’t crush you.

But to Lee and her classmates, every experience seems to be a message from the universe about their place in it. If an athlete jokes with Lee, calling her by her last name, that may be a sign that she’s higher than she thought in the social hierarchy that is imprinted on her brain. If her friends see her family’s blue Datsun roll up on Parents’ Weekend, they’ll know immediately she’s a scholarship student. If the boy she likes visits her room at night, it will mean that not just he, but fate, has chosen her, that she’s desirable, maybe even cool if word of their assignations gets out. Because everything is new to Lee and her friends, each day is vital, a harbinger of what The Rest of Life holds. “Once, I had imagined that the first boy you were involved with was your initiation, that after him the switch had been flicked on and you dated continuously,” Lee says. “But, at least in my own case, I had been wrong.”

There are times in “Prep” when Lee finds the huge significance attached to each act exhilarating. “To play a great game of high school basketball – it was something I myself had never done, but I could tell – made you know what it was to be alive. How much in an adult life can compare to that?” she muses. Even the uncertainty of her so-called life takes on a sheen of romance when she reflects on it in hindsight. “I think, looking back, that this was the single best thing about Ault, the sense of possibility,” she observes. “Depending on circumstances, a wild fact could be revealed to you, or you could fall desperately in love.”

But to the reader, Lee’s nonstop surveillance of who she is and is seen as and will be is nothing short of exhausting. Following Lee through unrequited love, unremarkable academics, and incredible embarrassments both avoided and endured takes you back to the uncertainty and fear, the hopefulness and mystery that characterizes high school, whatever your experience there. Unlike teen movies populated with mini femme fatales, “Prep” makes you both wistful and thrilled that you’re no longer a teenager, that you now have the power to decide what to eat for lunch, where to eat it, and whom to sit with during the meal. Having read and enjoyed “Prep,” I’m impressed with Ms. Sittenfeld’s powerful, evocative prose, and newly content with my own life. But I do worry about Mary-Kate and Ashley Olson.

Ms. Gage’s “North of Ithaka: A Journey Home Through a Family’s Extraordinary Past” will be published in May by St. Martins.