Two national giants better known for their guides to colleges and test preparation are getting into the game of rating New York City high schools.

Such guides have long been the domain of local authors and non-profit groups. But Princeton Review has released “Best New York City Private & Selective Public High Schools,” a book that includes profiles of more than 70 schools.

The book includes an earnest passage titled “Popular Private School Misconceptions Debunked,” which explains that not all private school students are rich, and not all schools are the same. It also includes some statistical morsels on admissions rates, requirements, and even median SAT scores.

U.S. News & World Report magazine (this reporter’s former employer) is going to give high schools across the country another jolt this December, when it releases a ranking of America’s 500 best, 1 through 500. The rankings depend on standardized test scores, graduation rates, and other data made widely available by President Bush’s No Child Left Behind law. As a result, the magazine’s editor, Brian Kelly, said, the rankings will not include private schools.

But Mr. Kelly said that doesn’t leave out the possibility of eventually including private schools. “We’d love to,” Mr. Kelly said. “If we can make apples-to-apples comparisons, we will.”

Mr. Kelly said he expects the public school rankings will raise debates just as the magazine’s rankings of colleges have. “I think it has the potential to spur a lot of civic discussion. And that’s great, I think that’s terrific. Let everybody fight it out at the school board meetings,” he said. “We’ll see how many mayors step forward and see if they want to fix some things.”

Random House ushered the nearly 300-page Princeton Review guide onto shelves in the city and across America this fall, and though he would not release specific sales figures, the book’s editor, Adam Davis, said interest so far is strong.

Mr. Davis said that final sales figures will give a better sense, divulging just how badly readers across the country care to know that the Birch Wathen Lenox School on the Upper East Side admitted only 20 of 120 applicants this year, compared to 17 of 18 at the Beekman School 27 blocks south; that 78% of girls at the Chapin School are white, compared to 76% of girls at Brearley, 74% at Nightingale-Bamford, and 71% at Spence, or that tuition at Riverdale Country School in the Bronx is $31,200, while nearly every other school that disclosed it did not top $30,000. (A school for children with learning disabilities, Churchill, costs $32,500.)

Ratings have been mixed so far for the new television show “Gossip Girl,” whose promise to dispatch weekly scandals from a fictitious Upper East Side girls’ school rattled some real-life girls. But the show made a most-downloaded list on iTunes twice recently, and it was reportedly the first series to be accepted for a full 22-episode run this season.

The Princeton Review guide dismisses the “Gossip Girl” image of an alternate universe for the extremely wealthy, waging a kind of correction campaign in a section on private school myths. “The truth is that at many New York City private schools, more than one in three students receive some type of financial aid,” author Alex Altman, a former New Yorker who taught tennis to Manhattan private school students, writes.

He also dismisses the idea that private schools are racially homogenous, saying that though they “may not quite match the United Nations’ standard,” the schools tend to have at least 20% students of color.

The private schools were initially wary of The Princeton Review’s interest. Mr. Davis said that when writers began contacting schools to get details on tuition, selectivity, and enrollment as well as basic information about the school’s atmosphere and curriculum, “the news kind of spread like wildfire.” Not all schools wanted to participate at first, and many in the guide were tight-lipped.

One Upper West Side school, Dwight, was an exception, disclosing the exact number of applications received versus accepted versus enrolled, 300 versus 80 versus 50, as well as its’ students’ precise median SAT score, 1205. Other schools not in the top tier of private schools known as the inner circle also divulged details, such as several competitive Catholic schools and selective public schools.

The nearly 300-year-old Trinity School, also on the Upper West Side, was an extreme example of schools’ more typical reserve. Trinity gave the size of its endowment, $29 million, and the date it was founded, 1709, but few other numbers, and it appeared not to have offered officials or alumni for interviews, as other schools did. The Princeton Review’s entry repeatedly cites the school’s Web site.

Mr. Altman said the company expects the schools to become more open as the guide acquires a reputation. “What happens often is that for the first edition of the book, schools aren’t necessarily as excited as they become later on to give you all the information that they have available,” Mr. Altman said. But, he said, “When they see how well-rounded some schools’ profiles are, they quickly toe the line and end up getting better information in further editions.”

The author of the locally produced Manhattan Family Guide to Private Schools, Victoria Goldman, said she could understand the temptation to create a review in a market whose competitiveness can make parents hungry for information. She said she compiled her own guide in 1994 after finding the process of getting her nursery-school aged children into private schools a nightmare with no information available. “You couldn’t get boo,” she said. “And here I was, thinking, I’m going to spend $250,000 a kid, and I can’t even find out what the scoop is.”

The book that resulted, a compendium of reviews that go on for as long as seven pages that has been called “the Bible” for Manhattan private schools, took two full years to research, she said.

By comparison, she called the Princeton Review Guide a disservice. “The key pieces of information are missing,” she said. “How many hours of homework can you expect to have a night at any of these schools? How competitive are they? What are the English courses and math courses? What is the rigor of the school? What are the parents like? When you go to high school, that’s really, really important.”

Ms. Goldman said she doubts the Princeton Review book will sell well enough to warrant a national market. Her book, she said, sells between 4,000 and 5,000 copies each year.

A consultant who advises parents searching for private schools, Robin Aronow, said the effort could be an attempt by Princeton Review to build brand loyalty among a population that is hungry for help.

Adding to a rich market of consultants and test preparation companies, Princeton Review already publishes guides to the tests that determine admission to private and selective public schools and offers preparation courses.