Administrators at three of the 12 professional schools said they will likely follow Yale College and the Graduate School of Arts and Sciences in adopting a new calendar that adds an October break in fall 2012.

In addition to adding a five-day fall break to Yale College’s first semester, the new calendar shortens reading and finals periods by two days each. Administrators at the Yale Divinity School, the School of Music and the School of Public Health said they will probably adopt the new calendar, while other schools said the new calendar may not be compatible with their existing schedules and needs.

“It is desirable for as many moving parts of the University to align as is reasonable and practical for their schools,” Yale College Dean Mary Miller said when the calendar was released Monday.

University Secretary Linda Lorimer said in an e-mail Tuesday that she distributed the proposed calendar to the professional school deans last summer. Lorimer said she asked the deans to notify her of any concerns, because many schools have students cross-registered from other schools.

Anne Pistell, associate dean for student affairs at the School of Public Health, said the school has used the Yale College calendar for the past several years and will adopt the changes announced Monday.

“We have the B.A./M.P.H. program, we cross list some courses with Yale College, and our Ph.D. students are enrolled in the Graduate School, which follows the Yale College calendar,” she said in an e-mail Thursday. “It is best for us to remain consistent.”

Divinity School Dean Harold Attridge said adopting Yale College’s new calendar will only require “minor changes” to the current calendar, so the school will probably make the switch. He added that he and his colleagues will make a decision later this semester.

But switching to a new academic calendar presents logistical challenges to some of the professional schools. School of Music Deputy Dean Paul Hawkshaw said he wants the school’s calendar to align with those of the other professional schools, but it would disrupt the current concert schedule. If the entire University has left for vacation, he said, it does not make sense to have a performance.

“I think we probably will [adopt the new calendar],” he said, “but I just think we need to see what the implications are for everyone involved.”

The performance schedule of the Drama School and Yale Repertory Theater is irreconcilable with the Yale College calendar, Dean James Bundy DRA ’95 said in an e-mail. Bundy said the institutions’ calendars have not aligned with that of Yale College for several years.

It is unclear whether the Nursing School will adopt the changes, Dean Margaret Grey NUR ’76 said in an e-mail Wednesday. The Nursing School must first ensure that students have ample time to complete clinical hours before taking required certification exams. She added that switching to the new calendar would be beneficial because the school offers a joint degree with the Graduate School.

The curricula of the School of Medicine and Law School may not directly transfer to the new calendar, said Medical School Deputy Dean Richard Belitsky and Janet Conroy, director of public affairs for the Law School.

Law students do not take exams until January, while Yale College and the Graduate School both have final exams before winter recess.

The new calendar will lengthen Yale College’s winter break by between two and five days, depending on the year.

Melissa Cail, Nikita Lalwani and Traci Tillman contributed reporting.