Northwestern will increase its undergraduate tuition by 4.8 percent next year, up nearly $8,000 since 1997, a university spokesman said Wednesday.

The Board of Trustees voted Saturday to raise next year’s tuition to $25,839 from the current year’s $24,648, the third year in a row that the university has raised tuition about 5 percent.

Graduate school tuition will increase 6.6 percent to $24,840 next year, and medical school tuition will rise 4 percent.

Alan Cubbage, vice president for university relations, said the increase covers the rising costs of university materials and labor.

“The challenge we face is that the costs we incur are going up much more quickly than the Consumer Price Index,” he said. “You can look at inflation, but that doesn’t really tell you the whole story.”

For students in a double room on the 16-meal plan, room and board rates will increase nearly 6 percent to $7,747 from $7,320. Cubbage said this amount covers increasing utility costs, dorm maintenance and debt service on bonds for Kemper and Slivka residence halls.

The increase brings next year’s undergraduate costs to $33,685 – less than the University of Chicago, Stanford and most Ivy League universities, Cubbage said. In a group of 18 major private universities, NU ranks 16th, or about $1,000 below the median, Cubbage said.

To offset the burden of higher tuition, Cubbage said NU will increase financial aid grants by 5 percent. About 60 percent of NU students currently receive financial assistance, he said.

“The university has a policy that whatever amount the tuition increases by, grants increase by the same amount,” he said. “Students shouldn’t see a reduction in aid.”

In 1998 NU hiked tuition by nearly 17 percent, from $19,152 to $22,392, and tuition has risen steadily each year since.

Although NU will continue to increase tuition to cover rising costs, administrators have no plans to institute another large tuition increase, University President Henry Bienen said.

“The period of fairly large tuition increases is probably over,” he said Wednesday during his annual State of the University address at McCormick Auditorium.

Bienen attributed the tuition increase to the rapidly rising cost of university materials, such as library books and journals.

The cost of journals for the library increased between 7 and 9 percent last year, straining the library’s $7 million budget, said Diane Perushek, assistant university librarian for collection management. The library subscribes to about 40,000 journals each year, she said.

Although a cutting-edge research collection plays a key role in expanding NU’s national reputation, Perushek said, student tuition should not bear all the burden for the increase.

The library also purchases 60,000 new books each year, with the average book price increasing 3.8 percent last year, she said. Expanding NU’s library helps attract highly qualified faculty, Perushek said, and lets professors pursue advanced research projects.

“Libraries all over the country are worrying about this,” she said. “We’ve been lucky in that we haven’t had massive cuts in periodicals.”

Associated Student Government President Adam Humann called the increased tuition “aggravating” but said NU is merely following the lead of other universities.

“I don’t appreciate that the cost of higher education is jumping every year,” said Humann, a Weinberg senior. “But it’s a national problem. It’s not just a Northwestern problem.”