Esther Barazzone told more than 100 skeptical alumnae and others Wednesday night that that income from growing graduate programs is being used to offset losses in the undergraduate women's college.
She cited declining enrollment, increasing costs and decreasing contributions to the annual fund, which fell from $1.3 million in 2007 to about $600,000 this year.
"It was a sad day for me to realize that Chatham College for Women needs to change in order to preserve our mission to women," Barazzone said.
The undergraduate college in Shadyside was founded as the Pennsylvania Female College in 1869. Officials said the freshman class has shrunk nearly 50 percent since 2008, and a college that once had more than 700 students could have fewer than 320 within five years.
Sarah Ford, a 2008 Chatham graduate, was among a number of speakers questioning the decision and urging school officials to reconsider.
"Going coed is the equivalent of selling your body. It will relieve the immediate financial pressure, but how will you look at yourself in the mirror?" she said to applause from the crowd.
Ford, 27, and other alumnae also questioned whether officials had done enough to enlist graduates to help recruit women, saying her repeated offers met little response.
"That is infuriating to me," she said. "You have an army of smart, capable and enthusiastic people."
Stephanie Swift-Antill, 34, accused officials of misplaced spending priorities over the years, including spending large sums on the new Eden Hall campus about 19 miles away from the main campus.
Chatham will study input from students, faculty, staff and alumni before the trustees meet again in June. If approved, the school could enroll its first male undergraduate students by fall 2015.
Some women's-only colleges are thriving, but the number of women's colleges in the United States has declined from more than 200 in the 1960s to fewer than 50 today -- and colleges that admit only men have become coeducational even more rapidly.