STATE COLLEGE - In an attempt to fight identity theft, Penn State University is ending a long-standing practice of using Social Security numbers to identify students.

A new nine-digit number went into effect today. Penn State was advising students and employees to keep their old ID cards with Social Security numbers until they were sure the new cards would work for all purposes at the highly automated university. The university has been working on the conversion for more than a year, according to Gary Augustson, vice provost for information technology.

Penn State officials would not estimate the cost of the conversion for its more than 80,000 students, thousands of employees and records for its half-million former students.

"Colleges and universities should have taken this step several years ago," said Linda Foley, co-executive director of the Identity Theft Resource Center in San Diego. "Because they didn't, college students are one of the three segments of the population most at risk of becoming victims of identity theft, along with senior citizens and military personnel."

But some students disagreed. Todd Lewis, a Penn State junior from Lancaster, said he doesn't like having to remember another number, and he and his friends thought it was a hassle to get new photos taken for ID cards.

"I think it's a waste," Lewis said.

State College police Sgt. Mark Argiro said the new ID numbers could slow police work, but he agrees with the move.

"These kids are 18, 19, 20 and they don't have the skepticism like I do," Argiro said.

Penn State is following a national trend in moving away from the use of Social Security numbers. The University of Wisconsin, Colorado State University, Lebanon Valley College, Shippensburg and Temple universities have done the same.