Washington-area colleges have run out of cheap, on-campus housing, forcing thousands of students out into the area's rapidly escalating real estate market to compete for a dwindling supply of affordable housing.

Rising rental prices, the conversion of thousands of low-rent apartment buildings into expensive condominiums and the desire of many students to experience the classic "college life" has produced a demand for on-campus and college-sponsored housing that Washington-area schools cannot fill.

There are about 22,000 housing units for students among the colleges and universities in the area that provide such housing. However, about 51,000 full-time undergraduate and graduate students are eligible for and would like to live in college housing, leaving the remaining 29,000 students to search for reasonably priced housing off campus.

Howard University freshman Henry Shaw said he arrived at school last fall expecting to move immediately into a room that had been reserved for him.

"When I walked into the room, four people were already sitting in there and there was no room for anyone else," said Shaw, who is from Asbury Park, N.J.

Shaw said he took a room at the Thomas Circle Holiday Inn to await word of his new room assignment. Three weeks and $250 in motel rent later, it came: Apartment 215 at 1230 13th St. NW, which Shaw shares with three other students.

Just a decade ago, colleges around the country were left with large numbers of empty dormitory rooms as students by the thousands moved off campus in pursuit of more social freedom and in protest of the restrictions that went with dormitory living.

"In the early 1970s, it was more popular for students to move off campus into their own apartments," said Frank Persico, associate dean of students at Catholic University, where 1,864 of the school's 1,922 dormitory spaces are occupied.

"Now we find that more and more students are moving back on campus each year," Persico said. "It's the cheapest form of housing in town. It's great for their social life. And they save on commuting expenses."

Howard University, which operates a dozen residence halls on campus, has leased three downtown apartment buildings since 1976 and is housing some students at the Woodner Hotel on upper 16th Street NW in an effort to keep pace with the growing demand for university housing.

"We've had a problem providing enough student housing for a number of years," said Edna M. Calhoun, dean for residence life at Howard. "But the problem has become more acute in the last three or four years because so much off-campus housing has been lost to condominium conversions."

Like all the other colleges in the area, Howard maintains an off-campus housing referral office that provides students with a list of homeowners and landlords near the school willing to rent rooms and apartments to students.

At George Mason University, there is a waiting list of 400 students who want to live in the university's 496 domitory units, which are filled. Some 500 additional dormitory rooms are under construction and are scheduled for occupancy by next January, according to officials.

Under a new policy it will implement next fall, American University will give first priority to incoming freshmen, leaving thousands of upper-classmen to fend for themselves in the highly inflated real estate market of Upper Northwest.

"When our students go out to look for housing, the main problem they run into is the high rental prices," said Emily Raffel, 33, a counselor in the university's student housing office and a senior majoring in American Studies.

"A lot of homeowners in the area rent out their basement to students, often allowing them to work off the rents in exchange for child care, general house work or yard work," added Raffel, who said she is having housing problems of her own.

"For seven months I have been house-sitting for a family that went to live in their house in Maine," she said. "Now the family is coming back and it's really tough to find a place that rents for the $200 a month I can pay."

Gay Fischetti, director of housing services at Georgetown University, said the school guarantees housing to imconing freshmen and uses a computerized lottery to determine which returning students will be assigned to university housing.

Two years ago, Georgetown added to its student housing the 300-unit Alban Towers apartment building at Massachusetts and Wisconsin avenues.

Gary Miller, director of investment properties at Georgetown, said the building is open to the public, but that students have priority over other applicants. There are 400 students among the current residents.

Since 1970, George Washington University either has bought or converted four buildings to student housing and has purchased the 175-unit Francis Scott Key Hotel, at 600 20th St. NW, to house students.

Two buildings, Munson Hall at 2212 I St. NW and Milton Hall at 2222 I St. NW -- once reserved for graduate students -- were converted to undergraduate student housing this year.

"Last summer we had a waiting list of 500 students and were only able to place half of them when the school year began," said Ann Webster, director of housing.

"To alleviate the problem, the university decided to move undergraudate students into Milton and Munson halls as graudate students move out," Webster said.

At the College Park campus of the University of Maryland, waiting lists for housing in recent years have occasionally risen to 2,000. A new dormitory is being constructed that is scheduled to house another 400 students by next January.

But Jan Davidson, director of student housing on campus, said the new facility is expected to fall short of mounting housing demands.

"Our school is very much a commuter institution," Davidson said. "But many students want to live on the campus because it gives them easy access to their professors, the library and other academic resources."

Krisandra French, a sophomore chemistry major at College Park, said that during her first semester she commuted to classes from her home in Sterling, Va. -- 50 miles away -- as she waited to be assigned to a univeristy dorm.

French, now happily settled in a room on the seventh floor of Centreville Hall, said the commuting was exhausting and she felt partially cut off from some aspects of college life because she did not live on campus.

Dee Lyons, a senior studying foreign service at Georgetown, said she lived on campus her first two years, studied in Switzerland the third and decided this year to rent a house off-campus with friends.

Their search for a house that five people could afford took them out of Georgetown to Capitol Hill, where they found a large town house renting for $500 a month.

A similar house in Georgetown near the university would rent for a minimum of $1,000 a month, said Lyons, who commutes the three miles to classes on a bicycle.

"I would like to move into university housing because my apartment has gotten too expensive," said Ben Noovel, a senior in mechanical engineering at George Washington University, who shares a one-bedroom Arlington apartment with another student.

"Right now, we pay $360 a month, plus utilities," said Noovel, who is on a waiting list for university housing. "An apartment at the university would cost us only $230 a month and we wouldn't have the expenses and the hassle of commuting."

Across the street from Eton Towers, an apartment building at 1239 Vermont Ave. NW leased by Howard University last year as a residence for women students, a half-dozen prostitutes strolled the street corners.

"I'm really glad I was able to get a room," said freshman Susan Ellis as she viewed the scene. "But I wish the univeristy could do more to regulate the environment."