Yale College enrollment will rise to 5,900 — an increase of 12 percent — if the University builds two new residential colleges, according to officials examining Yale’s proposed expansion.

The proposed increase of about 600 students, which would be the largest change in College enrollment since the advent of coeducation in 1969, would come at a time when Yale’s admission rate is at the lowest in its history, offering the University the chance to achieve its long-stated goal of admitting a greater number of qualified undergraduates. Any new colleges would also provide enough additional housing to decrease the size of colleges that must currently annex some upperclassmen to dormitories outside of their college, officials said.

Yale would not be alone in augmenting its enrollment. Princeton University is in the process of increasing its student body by 11 percent over the next five years, and Stanford University announced earlier this month that it would begin considering expanding undergraduate enrollment.

Yale College’s enrollment has hovered slightly above 5,000 students since the 1970s. In contrast, Harvard and Stanford both have 6,700 undergraduates.

The Yale Corporation will decide whether to go ahead with the expansion in February. Two committees charged with presenting a report about the expansion to the Corporation in January held two open forums with the Yale community last week and have three more planned for this week.

The new colleges would house 360 students each, said William Sledge, a former Calhoun College master who chairs the student-life committee exploring expansion. At the same time, the University would reduce the number of students in the existing 12 colleges by 150, to 175 students, which would allow colleges to reduce the number of upperclassmen forced to live on Old Campus or in off-campus apartments because their own college is filled to capacity, Sledge said.

In addition, rooms designed as singles but turned into doubles to alleviate space constraints — particularly in Lanman-Wright, which houses freshmen in Pierson and Saybrook colleges — could be turned back into one-person rooms, Sledge said.

More admits

Other constituencies could benefit, too. At a forum last week, Dean of Undergraduate Education Joseph Gordon, the chairman of the committee reviewing the expansion’s impact on academics, said an expanded enrollment would allow the University to accept more legacy students.

The expansion would likely have a marked effect on Yale’s admissions rate. Last year, the University admitted 9.6 percent of the more than 19,000 students who applied — a 0.7 percent increase from the previous year’s record low.

Last year, the University accepted 1,860 students for 1,318 slots. Assuming Yale’s yield remains the same, a 12 percent enrollment increase would mean Yale could have accepted about 220 additional students last year, making its admission rate 10.8 percent.

Dean of Undergraduate Admissions Jeff Brenzel said it would be “very premature” to speculate on how any expansion might affect Yale’s admission results or recruiting efforts. But he said the University’s financial aid budget would increase as necessary to support any rise in enrollment.

“The basic thing to remember is that each year we turn away thousands of exceptionally qualified students of all kinds, and that expansion will provide a significant number of additional students with the opportunity to engage Yale’s extraordinary resources,” Brenzel said in an e-mail.

Such an increase in enrollment, while increasing tuition revenue, would not be a profitable endeavor. In this fiscal year, Yale will earn $156 million in revenue from undergraduate tuition, room and board after the cost of financial aid, according to University budget projections. If these data are an indication of the future, a 12 percent increase in enrollment could bring Yale an additional $18.7 million annually.

But the overall increase in enrollment, even putting aside any increases in faculty, staff or support services that would certainly be necessary as a result, would result in a net cost, Deputy Provost Chip Long said. The true cost of housing and educating a student is significantly greater than the sum of tuition, room and board — perhaps as much as double what a student with no financial aid would pay annually, Long said.

A new Old Campus?

Any expansion could have a notable effect on Yale’s housing system. McClellan Hall on Old Campus, currently used to house annexed students in Trumbull College, could be used as a permanent residence hall for Jonathan Edwards College upperclassmen, much as Rosenfeld Hall is for Timothy Dwight College students, committee members said during last week’s forums.

The dozens of suites occupied by annexed upperclassmen in other Old Campus dorms could be used to increase the number of graduate students and faculty living on Old Campus, they said. Some of the suites could be “rented” to upperclassmen from different colleges who want an opportunity to live together without having to find off-campus housing, committee members said.

An increase of 600 students would not be the largest in Yale’s history. The College increased from about 1,500 students before World War II to 2,500 students after the war, according to statistics compiled by the Office of Institutional Research. Between 1950 and 1975, enrollment in the College increased from 2,533 to 5,144 students.

The University will hold three more student forums on the proposed expansion. The forums, scheduled for 9 p.m., are planned for Tuesday in the Saybrook College common room, Thursday in the Morse College dining hall and Nov. 5 in the Silliman College master’s house.