As college students across the country settle into their dorms and class routines this month, many of them are feeling the lingering pinch of an unexpected bill: the high price of college textbooks.

Though the dramatic increase in college tuition in recent years is well known, students and parents are finding that the costs keep coming even after a student is on campus, as many textbooks can cost well over $100.

Some college and public-interest groups charge that the publishing industry is forcing textbook prices higher by introducing unnecessary new editions and packaging books with expensive study materials that not all students want or need. The National Association of College Bookstores says wholesale prices of college textbooks have risen nearly 40 percent in the past five years.

And students are finding that many of the same books are sold overseas at much lower prices.

Some students are getting more aggressive about buying used books, when possible, through multi-campus Web sites such as Books on Campus and DogEars. And some schools are also establishing and promoting used-book exchanges to help students. The really resourceful on campus have even gone as far as ordering their books from overseas Web sites, where prices can be significantly cheaper for new books -- though doing so means a longer shipping time and no returns.

Industry experts say that it is hard to measure the impact of the alternative sales channels and that some of it may be masked by price increases.

The $3.4 billion-a-year higher-education publishing industry says that it must keep its material current to win schools' support and that prices are competitive in each market. Industry officials defend new editions churned out by major higher-education publishers Thomson Learning, Pearson Education and McGraw-Hill. They argue that texts must be continually modernized if publishers want to keep the attention of today's college students, who are used to the graphics and interactivity of the Internet.

The debate has even landed in Congress, where hearings were held on the matter this summer, and legislators asked the Government Accountability Office to launch an investigation of college textbook prices.

"If a student signs up for a class, they're pretty much at the mercy of the publishers," said Rep. Howard P. "Buck" McKeon (R-Calif.), who led the hearing. "It's not like they have any other place to go."

McKeon and others claim the academic-publishing industry has insulated itself from traditional market forces to increase profit. The constant reissuing of editions, in particular, is viewed as a way to force professors and students into using and buying new books.

A study this year by the California Student Public Interest Research Group found that the average release time between textbook editions is 3.8 years, regardless of whether the information has changed since the previous version. Of the textbooks surveyed, new editions cost 58 percent more than the older version, rising to an average cost of $102.44.

Laura Nakoneczny, a spokeswoman for the National Association of College Bookstores, complained that new editions also are coming out more frequently than they used to, "maybe every three years instead of five years," she said.

That turnover means that students can't buy cheaper, used textbooks as often as they once could because older versions are quickly out of date. "We know that some kids are just not buying the books," she said. "And that defeats the whole purpose of a college education."

Some academics say the churning out of new editions is designed purely to increase profit for the publishing giants.

"Publishers make their money on new books," said John Pease, an associate professor of sociology at the University of Maryland at College Park, who has been closely following the textbook-pricing issue. "Once they've published a textbook and there's a zillion of them out there -- that's it for their profit until they can come up with a new edition or some sort of technique to sell more books."

One of the techniques Pease and others cite is the "bundling" of books with other materials, such as study guides, Web site access, test questions, CD-ROMs and more. These add-ons are helping to drive up the cost of books.

Publishers say new editions are aimed at including newer teaching techniques and more modern information or interpretations, even in more stable disciplines like history. "When you had a history book, it was all about dead white men -- today you have to make sure women and minorities are well-represented," said J. Bruce Hildebrand, executive director for higher education for the Association of American Publishers.

Professors also like to order books that have more interesting charts and graphics because students respond to them, Hildebrand said. "The newer the copyright, the greater the demand because of the way books are being redesigned," he said. But those fancier pictures and more thorough flow charts are expensive to design and pay royalties on, he said.

Moreover, Hildebrand said, most textbooks can be ordered in less expensive versions, even in a black-and-white, three-ring-binder version that might only cost $25, while the fully loaded book might push $120.

There is debate in the academic community about whether professors are sufficiently informed of the costs -- and the alternatives. "If you're a commissioned sales rep, it's not necessarily in your interest to promote the availability of those items," said Nakoneczny of the college stores association.

The University of Maryland's Pease also said there are plenty of faculty members who simply aren't aware of book prices. "They haven't thought about it, and they're busy and they're doing other things," he said.

Professors may be unwittingly contributing to the rising costs of textbooks. Publishers say professors are asking for more content for teaching and learning, which is leading to the addition of so many learning tools. But if the professor does not specify that those extras should be sold separately, they are likely to be bundled with the book at a single, higher price -- and students have no choice but to buy the entire package. The study by the California Student Public Interest Research Group found that the practice of bundling books with non-required materials rose 21 percent between consecutive editions.

Hildebrand defends the lower prices publishers charge overseas, arguing that U.S. publishers have to price books lower there to break into a market. Book prices here might be higher without that added volume, he said.

"It's a way to hold the overall price down for both sides of the pond," he said.

Maryland professor John Pease is frustrated with the practice of bundling college textbooks with other materials, such as study guides, making the books more expensive.