So they may not have gotten into their dream schools, but most high school seniors have already decided where they will go to college next fall.

But wait, what's that sound? It could be Harvard knocking.

There is still hope for a few hundred in the class of 2008 who got turned down by elite colleges, some of which are turning to their wait lists this year to fill out their incoming classes.

"Around May 1 many of us found we had fewer students in class than we like to have," said Eric J. Kaplan, interim dean of admissions at the University of Pennsylvania.

As a result, a few hundred lucky students may get a second chance at their dream schools. Penn plans to offer admission to 90 students from its wait list of 1,352, and Swarthmore College said it would reach out to about 20 of the 350 students it has in reserve. Last year, Penn took 65 and Swarthmore about 15.

Kaplan attributed the shortfall to changes in admission policies at Harvard and Princeton Universities that caused those schools to dip into their wait lists. That resulted in a trickle of students spurning other institutions.

Harvard said it would make offers to 150 to 175 students on its wait list, and Princeton said it expected to take 90.

The domino effect could go on all summer, said Jim Bock, admissions dean of Swarthmore, which will have 370 in its incoming class.

"Harvard may take someone from Brown, Brown may take someone from Swarthmore," he said.

Just recently he offered a spot to a wait-listed student who in April had written him a letter "expressing her sheer and genuine love for Swarthmore," he said.

She turned him down.

"She said, 'Why didn't you just take me in April?' " he said. She didn't tell him where she was going instead.

Highly competitive colleges and universities generally don't need to dig into wait lists because there are always many more applicants than places.

The difference this year is that Harvard and Princeton eliminated early decisions, so students took longer to decide and applied to more schools than in the past, Kaplan said.

Also affecting admission was the change in the financial landscape, with some high-end schools giving enhanced aid packages to lower- and middle-income students.

"If students are less worried about financial aid, they can choose more where they'd like to go to school rather than where the best deal is," Kaplan said.

Most schools send out acceptance letters around April 1 and expect commitments by May 1. Bock said that he liked to get his class set by June 1 but that the process might drag into July this year.

By August, schools are beginning to recruit the next year's class.

Kaplan said Penn came very close to its goal of a 2,400-student class. Because some students will "melt" to other schools, and others will defer a year, the school wants to build up its numbers, he said.

At Bryn Mawr College, Jenny Rickard, dean of admissions and financial aid, said that although the school had enough students to fill its class, "It all depends on the overlap of admissions."

"Sometimes it seems like the same 300 students are being shifted around," she said.

Haverford College is also on target, but Jess Lord, dean of admissions and financial aid, said the school was waiting "for the dominoes to fall" as Harvard starts drawing from its wait list.

For students, playing the admissions game this late in the year can be stressful.

"It creates more confusion," said Anne Hall, director of college guidance at Episcopal Academy in Merion.

Five Episcopal students have been whisked off wait lists, she said, a few more than normal. Of those, only one has said yes.

It's hard for students to be turned down by their dream school, then wooed by another college, then told by the first one that they can come after all.

"It would have been nice if these decisions had been made by the colleges initially," Hall said.

Contact staff writer Kathy Boccella at 610-313-8123 or kboccella@phillynews.com.