Continuing a long-term trend, the acceptance rate at many of the country's most selective colleges inched down this year to ever-more agonizing levels for parents and students.

Harvard (7.1 percent), Yale (8.3 percent) and Stanford (9.5 percent) were among the growing number of schools where more than nine in 10 applicants were denied. Middlebury (18 percent) and Duke (19 percent) were among the many others reporting record selectivity.

But now, the pressure switches to colleges, who generally give students a month after April 1 admissions notifications to make up their minds whether to attend. If colleges admit too few students, they can end up with empty spaces. Too many, and they could get stuck housing extra freshmen in trailers on the quad.

This year, it's a bigger guessing game than ever. The decisions by Harvard, Princeton, and the University of Virginia to eliminate early admissions this year forced those schools to tear up decades-old models that allowed them to accurately estimate how many students who were admitted would actually come, decisions that trickle down to other schools.

Meanwhile, several dozen colleges, among them Harvard, Dartmouth, Swarthmore and Tufts, announced expansions of financial aid in recent months. No one knows exactly what effect that will have on students' choices.

"From an admissions perspective, it's been quite a chaotic year," said David Hawkins, director of public and research for the National Association for College Admission Counseling. "The story of the year seems to be the continued and even increasing uncertainty that faced both students and colleges."

"Without two big players in the game, you can't predict where someone has applied, where they've been admitted, and where they're going to go," said Jim Bock, dean of admissions and financial aid at Swarthmore.

Students who have just endured the process probably won't mind seeing the tables turned when it comes to anxiety.

Said John Blackburn, dean of admissions at Virginia: "It's been scary."

It's scary for students, too. With a population bubble increasing the number of teenagers, elite colleges can seem incredibly difficult to crack.

Swarthmore received a record 6,118 applications this year. That's a 66 percent increase from four years ago. And while the school has become ever more selective - only 15 percent were admitted this year, compared with 17 percent last year - Bock said the actual number of students admitted had increased. In April, 929 received acceptance letters. Last year it was 890.

Among other colleges releasing numbers this week, Princeton admitted a record-low 9.3 percent of applicants, Columbia 10 percent, the University of Pennsylvania 16 percent, Boston College 26 percent, and Virginia (which is state-supported) 38 percent.

Still, that's not quite the full story. Nationally, the average acceptance rate for colleges is roughly 70 percent, about what it was 20 years ago.

What has really changed is that more colleges are recruiting all over the country, and more students are applying to a large number of schools. The trend feeds on itself. Students apply to more schools, each school gets more applications, and the admissions rate goes down. Students get scared, so they apply to more schools. And the cycle continues.

But while it means good students are more likely to get rejected by at least some upper-tier schools, they are getting more acceptance letters, too.

U.S. Official Seeks To Offer Loan Aid

Education Secretary Margaret Spellings seeks to ease worries that tight credit markets might make it hard to get college loans.

Her aides reviewed the law and concluded that she has the authority to quickly free up money from the Treasury, if needed, to finance student loans.

The money would be given so that guarantee agencies - nonprofits that traditionally back student loans issued by banks - can offer loans directly in a pinch.

Students and others fear the credit crunch will make it more difficult to find loans. Nearly two dozen lenders have left the federally backed student loan program.

- Associated Press