SAN FRANCISCO

The University of California's governing board on Thursday unanimously approved a major overhaul of its admissions policy that will greatly expand the pool of undergraduate applicants but guarantee admission to fewer high-achieving students.

Set to take effect with the freshman class of fall 2012, the new eligibility standards adopted by the UC Board of Regents represent the biggest change to UC admissions policy in nearly 50 years. It is designed to give many more high school seniors a shot at attending one of the nation's top public universities.

The new rules will reduce the number of students guaranteed admission based solely on their grades and test scores, but increase the number whose applications will be eligible for a full review by an admissions committee.

Under the revised qualification requirements, applicants also will no longer have to take at least two SAT subject exams, which officials say blocked many otherwise-qualified students from seeking admission to a UC campus.

"You can't get much fairer than this policy," said UC President Mark Yudof. "We look at the whole student, and we look at more students ... It clearly will not diminish the qualify of the students."

Officials said the plan would encourage more students to apply and could potentially increase the number of low-income and underrepresented minority students.

Some critics described the new admissions policy as a way for the university system to skirt a 1996 ballot measure that banned affirmative action at public institutions in California — a criticism the plan's backers adamantly deny.

Asian American leaders in the state Legislature had urged the regents to postpone the vote to allow more study of the plan's potential impact on various ethnic groups. A regents committee gave the proposal preliminary approval on Wednesday.

Under current rules, the top 12.5 percent of the state's high school graduates — as well as the top 4 percent at individual high schools — are guaranteed admission to at least one of UC's ten undergraduate campuses, though not necessarily the schools of choice. Currently, almost all students outside those groups are automatically rejected.