ANDOVER, Mass. — When the elite Phillips Academy here went coed in 1973, some worried that women would quickly take over this venerable institution, the alma mater of Oliver Wendell Holmes, Samuel Morse and Humphrey Bogart, not to mention both Presidents George Bush.

In short order, the number of girls in the student ranks did roughly equal the number of boys. The faculty today is more than half female. And until her retirement last summer, the head of school was a woman, for nearly two decades.

And yet some of the young women — and men — at the 235-year-old prep school feel that Andover, as it is commonly called, has yet to achieve true gender equality. They expressed this concern several weeks ago in a letter to the student newspaper, The Phillipian, and like a match to dry tinder, it set off a raging debate that engulfed the campus.

The proximate cause of concern was the election, held Wednesday, for the top student position, called school president. Since 1973, only four girls have been elected, most recently in 2003. (The other top student position, that of editor in chief of the newspaper, has had nine girls and 33 boys.)