Kaavya Viswanathan is set on becoming an investment banker when she graduates from Harvard University in 2008, but a phone call that the 17-year-old freshman received from a literary agent might just cause a change in her plans.

The agent, Jennifer Rudolph Walsh of the William Morris Agency, told the Franklin Hills, N.J.-born Ms. Viswanathan that Little Brown & Company, one of the oldest and most prestigious American publishers – now part of the Time Warner Group – agreed to a two-book deal with the teenager. The sum approached $500,000, a staggering amount for an unpublished writer, let alone someone who’d barely left home for college.

“I still cannot believe this. I never expected this would happen,” Ms. Viswanathan told The New York Sun yesterday. “I had only vaguely thought of becoming a writer. But a book contract? From a major publisher? This is so incredibly unbelievable. It’s so hard to believe that I’m going to be able to walk into a bookstore and see something that I wrote on display there.”

Both her books will be fiction. Ms. Viswanathan said she expects to deliver the first volume, tentatively titled “How Opal Mehta Got Kissed, Got Wild, and Got In,” by the end of next month. The novel is expected to be published next spring.

Little, Brown’s publisher and senior vice president, Michael Pietsch, said last night through an aide that the company doesn’t comment on authors’ advances. Mr. Pietsch is handling Ms. Viswanathan’s book, along with another Little, Brown editor, Asya Muchnick. Most first-time writers of fiction receive advances of less than $10,000, according to the editor of Writer’s Digest Books, Donya Dickerson.

Ms. Viswanathan said she’s already written more than 150 pages, or more than a third of the manuscript.

“It’s a little tough to do this writing and also juggle classes and the homework,” she said. “This is a big-time commitment. It’s not like writing an essay for a class.”

Ms. Viswanathan began writing the novel while still at the Bergen County Academy at Hackensack. She’s the only child of her Indian-born parents, Viswanathan Rajaraman, a neurosurgeon, and Mary Sundaram, a gynecologist.

“Everybody in my family, including my parents, won science prizes,” Ms. Viswanathan said. “I was the one with the writing gene – and I’ve no idea where that came from. My parents are still in a state of shock. When I’ve gone home on some weekends, they look at me working at my computer and surely wonder, ‘Who is that strange person?’ “

Her parents, who are vacationing in India, could not be reached for comment yesterday. And how did Ms. Viswanathan’s novel come to the attention of Ms. Walsh at William Morris?

“My parents had gone to college in India, and they felt unfamiliar with the college-application process in America,” Ms. Viswanathan said. “So they signed me up with Dr. Katherine Cohen’s IvyWise as an extra safeguard.” IvyWise is a service that prepares students for college admissions.

“I always wanted to get into Harvard,” the teenager said, “and I received an early acceptance.”

Ms. Cohen said yesterday that when she saw Ms. Viswanathan’s resume, she wondered why the student hadn’t highlighted the fact that she was writing a novel. Then she asked Ms. Viswanathan to bring in her work.

“I was so charmed by what I read,” Ms. Cohen said. “I immediately sensed that here was a star in the making. So I called my own agent at William Morris, Suzanne Gluck, and told her about Kaavya.”

Ms. Gluck showed the manuscript to Ms. Walsh, who handles fiction at the agency. She was impressed and shopped it around, and Little, Brown offered the highest advance. Ms. Viswanathan was the youngest writer the agency had taken on in its 109-year history.

“I still remember the moment when Kaavya called me and said, ‘Have you heard? Have you heard?’ “Ms. Cohen said. “When I heard the size of the advance, I nearly fell off my chair. I have several novelist friends, and nobody I know has received that kind of money. I’m very proud of her – and I’m proud that I was able to play a role in her success.”

Strangely, Ms. Viswanathan’s novel is a case of life imitating art. Her plot was hatched well before she signed up with Ms. Cohen and was accepted by Harvard.

“The main character is a girl of Indian descent who’s totally academically driven, and when she senses from a Harvard admissions officer that her personal life wasn’t perhaps well-rounded, Ms. Mehta goes out and does what she thinks ‘regular’ American kids do – get drunk, kiss boys, dance on the table,” Ms. Viswanathan said.

Does her fictional character get into Harvard? Only the novel will tell.