Behind a gray house on a little street in West Cambridge, the asters and chrysanthemums are blooming in Mary Maples Dunn's garden. Herbs like tarragon and oregano grow in a small plot. Dunn often wakes early to tend the plants, her principal hobby.

"You're always transplanting and digging this up and putting that down," she says.

Dunn looks like your grandmother, with crisp white hair and a ruddy complexion, who stands just about five feet tall. She loves detective novels and just finished knitting a blanket for her first grandchild, who will be born next month.

When she resigned as president of Smith College in 1995, Dunn expected to retire to those pursuits full-time. When she changed her mind and accepted a post as head of Radcliffe's Schlesinger Library, she thought it would be her last job.

But now she might have her most challenging position yet.

The acting dean of the Radcliffe Institute for Advanced Study, who today becomes the only woman to head one of Harvard's 10 schools, Dunn will guide the new, $350 million Institute through its first critical days of self-definition.

Dunn comes to the helm after a long career in women's education. First a professor of colonial women's history, she became dean of Bryn Mawr College and president of Smith College, and later director of Radcliffe's Schlesinger Library.

At Radcliffe, where secrecy and closed doors have marked two years of negotiations, Dunn presents a striking contrast. She is easily accessible and friendly with students, having taught tutorials for history and literature concentrators and a first-year seminar.

"It was absolutely a delight to be able to work with someone as well versed as she is," said Cristin M. Hodgens '01, one of Dunn's students. "I think that she's really well suited to mentoring on every single level."

Dunn's wit and arch humor are famous among administrators and students.

Delivering the annual Radcliffe lecture last month, Dunn remarked on the linguistic gap between her generation and today's students, drawing a wave of laughter from the audience.

"In New England, 'wicked' has resurfaced as an intensifier or term of approval, which for someone my age is really weird," she told listeners last month. "'Sketchy,' when applied to a new acquaintance, is definitely not a compliment--though what it is is not clear to me. My students tell me on the DL, or 'down low,' that I'm really random. Whatever."

Agreeable and diplomatic, Dunn has won friends in every quarter--even from those with competing visions for Radcliffe.

"She's naturally cheerful," says Richard S. Dunn '50, her husband of 39 years. "She gets other people to work for her, which I think is a valuable skill."

That skill will serve her well as the Institute tackles the knotty problems--the future of women's studies, the choice of a permanent dean--that will shape her tenure.

From a Two-Room Schoolhouse

Sturgeon Bay, Wis., where Mary Dunn was born in 1930, is wedged on a narrow peninsula jutting into Lake Michigan. Dunn attended classes in a two-room schoolhouse there until the start of the Second World War, when her father, a haberdasher, was drafted into the Army.

After the war, he stayed in the military, and the small-town family traveled with him, including two years in China after peace was declared.

"It blew open my mind to the possibility of other cultures," Dunn says. "I was a kid from Wisconsin who was suddenly exposed to a much wider world."

After they returned to the United States, Dunn enrolled at the College of William and Mary in Williamsburg, Va., where she studied history.

Going to school in the segregated South, she says her understanding of racial discrimination grew gradually, particularly after the Supreme Court ruled in Brown v. Board of Education in 1954.

"You had to learn what it meant," Dunn says. "People accepted segregation very unthinkingly... My interest and engagement in the civil rights movement came in the '60s, but my understanding began in the '50s."

As a self-described member of "the campus left wing," Dunn cheered the decision on Brown. But even as her consciousness of racism grew, sexism remained more difficult to see, especially since Dunn grew up in the all-male world of the Army.

"[The] gender relations might seem odd to you, but it was normal for the 1950s," she said. "There was a 'dean of women,' women had parietal rules that were different from parietal rules for men."

But when she started graduate studies at Bryn Mawr, a women's college outside Philadelphia, her opinion changed.

"At first it seemed like an unreal kind of world...[but] I began to see how important it was," Dunn says. "I was in a place that was pretty much run by women and for women."

Dunn had trouble applying for positions in an academic world where female professors were scarce.

"I wrote endless letters trying to get jobs at various history departments but no one would give me a tumble," she says. She ended up teaching history at Bryn Mawr.

Dunn met her husband in 1959, then a professor at the University of Pennsylvania, and the couple were married in 1960.

Both Dunns were specialists on early American history, and they later edited a four-volume edition of William Penn's papers together. After their two children were born, Richard Dunn briefly substituted in his wife's classes.

"We could buy the same books and teach the same courses," said Richard Dunn, who heads a center for early American studies at the University of Pennsylvania.

Presidential Timber

Mary Dunn rose quickly into the administrative ranks and served as Dean of Bryn Mawr College for seven years. In 1985, she was tapped as president of all-female Smith College in Northampton, Mass.

At Smith, Dunn exhibited a low-key leadership style, especially when turmoil hit the campus.

In 1986, 200 students occupied College Hall, Smith's main administration building, in protest of the college's investments in South Africa. But unlike Harvard administrators who faced a similar situation in 1969, Dunn refused to call the police.

"There were a lot of people who thought I should call the cops and haul them out, but I didn't want to do that," she said.

The students remained in the building for a week, during which Dunn organized a series of discussions and open meetings with both students and trustees. Later that year, the board voted in favor of divestment.

Throughout the ordeal, Dunn's goal was simple: "To talk as much as possible. To find out what it was all about, to discover where we had common ground, to work together as much as we could," she said.

"Over the long haul," she adds, "students trusted me to tell the truth, and to deal with issues honestly as I saw them."

Dunn says she worked on making Smith a more welcoming place for minority students, drafting a "Design for Diversity" to raise aware of racial issues. She calls it her proudest achievement as president.

Full Speed Ahead

After suffering a heart attack and undergoing bypass surgery last fall, friends and family advised Dunn to slow down. But she again postponed retirement to be drafted as interim head of Radcliffe, a position she expects to hold for no more than two years.

"I think I'm going to retire, but then I thought that's what I was going to do when I left Smith," Dunn says.

Dunn is passionate about several nonprofit organizations on whose governing boards she serves.

"She loves to be on boards, but not boards that make money--boards that cost money," Richard Dunn says.

In particular, she is committed to the National Organization for Women's Legal Defense and Education Fund and to Music for Marlboro, a local music festival in Marlboro, Vt.

And she continues to take political stands. Last year she was one of a group of historians and scholars to sign a widely-circulated anti-impeachment tract.

But although Dunn is looking forward to the challenges of the next two years, her most important interest will lie at home.

"Any free time I have in the coming year will be spent grandmothering," she says. "The baby may even take precedence over the garden."