Hundreds of students blocked all entrances to the coastal campus and prevented vehicles from entering, said Josh Brahinsky, a graduate student and union representative who helped organize the action.
The protest at Santa Cruz is part of demonstrations being held by college students at about 30 campuses across California and was scheduled to coincide with state budget negotiations, organizers said. Rallies, marches, teach-ins and walkouts to call on lawmakers to restore funding to higher education were also planned.
The campus protests are a prelude to a major "Occupy the Capitol" rally in Sacramento on Monday. Dozens of students and faculty members plan to march roughly 100 miles from the San Francisco Bay area to the state capital over the next few days.
The protesters are calling on Gov. Jerry Brown to reject any budget deal that includes higher education cuts or tuition increases. They also want the governor to support a ballot measure that would raise taxes on millionaires to pay for education and social services.
"We've destroyed our tax base and we stopped funding the most important parts of our society," said UCSC's Brahinsky. "We're calling on the state to tax the wealthy and use that money to build services for all of us."
The demonstrations were coordinated by ReFund California, a coalition of student groups and labor unions that organized a series of sometimes rowdy campus protests during the fall.
At Santa Cruz, campus police briefly detained a motorist who tried to drive through a crowd of demonstrators, but no one appeared to be seriously injured, said campus spokesman Jim Burns.
"The campus has been effectively closed to vehicles," Burns said. "Clearly it's had an access impact for many students, staff and faculty."
School administrators had warned the campus this week about the protest. Many classes were canceled or rescheduled, and administrative offices were not fully staffed, Burns said.
College students across the country also were organizing protests Thursday to focus attention of education.
