Along with negotiation comes a lot of research. O'Brien and her two colleagues examine courses' past enrollment and location to determine room assignments.

Much of the work for the fall semester begins in May when FAS' Courses of Instruction is sent to the printer. The office is operating on a deadline: the supplement that appears in the mailboxes of students must be ready to print in late August.

However, each semester, some Harvard classes get an unexpectedly large turnout. What happens when the students don't fit in the classroom?

Yesterday, students crowded Harvard Hall for Government 1540: "The American Presidency," a popular government course taught by the Kennedy School's IBM Professor of Business and Government Roger B. Porter.

If the enrollment exceeds the room capacity, the course may need to be lotteried, Porter says.

But O'Brien says meeting professors' needs is the first priority.

"If we didn't have a room, [we'd look] at a change in time," O'Brien says.