One of the nation's largest college textbook publishers will offer a stripped-down line to cut 25 percent off prices, a move lauded by a student- led activist group that two weeks ago accused publishers of driving up textbook prices by adding "bells and whistles" and printing unnecessary new editions.

Thomson Higher Education said its announcement this week of the "Advantage Series" followed 14 months of product development and is not a response to the "Ripoff 101" report by the California Public Interest Research Group, known as CalPIRG.

The student group disagrees, saying the move to cut prices on 25 of the thousands of texts Thomson publishes is proof that the report has touched a nerve, and that textbook publishers can make changes that save students money. The books will come out in the summer and fall.

"We think it's a small step," said Merriah Fairchild, who wrote the report about college textbook prices. "It's not a home run."

The report surveyed 156 professors who assign texts at nine public universities and one community college in California and Oregon. Two-thirds of professors who responded said new editions of textbooks, which can cost more than $100 each, are justified only half the time or less.

The report also criticized the expensive bundling of books with extras such as CDs and workbooks. The textbook-makers say unbundled texts are available but aren't popular with professors.

Thomson does not agree with any of the report's conclusions, and it considered postponing the announcement of the new series to avoid the appearance that it was giving credence to the report, company spokeswoman Jessica Rohm said.

The new series of books will be cheaper because it will rely on fewer photographs and illustrations and fewer colors, while some versions will be offered in loose-leaf binders, Rohm said. She said Thomson has always offered "as much choice as possible."

Thomson Higher Education of Stamford, Conn. publishes 1,000 new texts a year, and has 10,000 books back-listed in subjects from the humanities to science to mathematics.

On Thursday, Fairchild met with Pat Schroeder, chief executive of the Association of American Publishers at the association's headquarters in Washington, D.C. Fairchild said her group is also asking college faculty members from around the country to send letters to the trade group.

While Fairchild characterized the meeting as a negotiation, Rohm said the group is "not going to influence any of the companies."