Husband (to wife, who has just gotten off the phone after an hour-long conversation with a girlfriend): What could you possibly be talking about for that long?

Wife: Nothing.

It's true. Unlike men, women don't need a reason to talk to a friend. With men, a telephone conversation or a get-together with a friend is usually need-based -- "Can I borrow your weed whacker?" or "Wanna go to the game Sunday?"

But for women, it doesn't work that way. Just "checking in" is reason enough to talk on the phone or get together. And when that happens, that "nothing" turns into a whole lot of "something" -- women talk about their feelings, their hopes and dreams, their miserable jobs, their blind dates, their therapy sessions, their aging parents, whatever is on their minds. This kind of meaningful sharing is the basis for many a deep and abiding friendship between women. And if two is good, 10 is better.

"Girls' Night Out: Celebrating Women's Groups Across America," a new book by Washingtonian Barbara Camens and her friend and fellow group member Tamara Kreinin, focuses on this phenomenon. The two traveled across the country, meeting with and interviewing a wide range of women's groups -- among them a local one that rides motorcycles, a collection of artists in Boston and some women who have been meeting for more than 50 years. "There is something valuable and special about women's friendships. [Women know] that good friends equals a good life, and they want to acknowledge the importance of that," says Kreinin.

It used to be that "women's groups" were a part of daily life. Sewing circles, quilting bees, bridge clubs, volunteer opportunities -- all of these activities gave women ample chances to to connect, confide and make memories together.

When Camens started her women's group 20 years ago, times had definitely changed. "We started our group because we were new to the city. We were very busy with our careers, but we had a sense of disconnectedness. We were away from our families, and we all felt the need [to belong to something]. Finding a community can be difficult, especially in an urban area." Like gardens and children, friendships need nurturing to grow and thrive. Certainly, one-to-one friendships can be very meaningful. But there seems to be something about the friendships created in the context of women's groups that makes them endure.

"You tend to honor the commitment you make to your group," says Camens. In other words, you may cancel or reschedule plans with a girlfriend, but it's hard to do that when 10 people are counting on you. "You get it on your calendar, and you go," Camens says.

Kreinin has found women's groups so valuable that she is a member of three of them. She used to live in New Orleans and still gets back there for meetings of GNO{+2} (Greater New Orleans Girls Night Out). Here in Washington, she is a member of Chicks 'n' Flicks, a movie-lovers discussion group, and also is a member of Camens's group. Kreinin lives in New York, but says that because there are only 24 hours in a day, she is "determined not to be in a group" there.

Chicks 'n' Flicks is one of the groups featured in the book. It consists of nine women whose common starting point was a love of cinema. Each month they choose a movie to see over the course of the next four weeks. They may see the movie together, in small groups or alone. As with a book club, the meetings are structured around discussions of the film. "We enjoy getting together to talk about film," says Jennifer Cortner, a longtime member of the 8-year-old group. But the fun part, she says, "has been seeing the friendships that have come about. It becomes less about the activity and more about just coming together."

Another local group featured in the book is the Phenomenal Ladies, from Prince George's County. Their camaraderie comes on the open road, on their motorcycles.

"We have a sisterhood," explains the group's president, Theoria Johnson, known as "Lady T." ". . . We just love to ride." In fact, learning to ride a motorcycle was cathartic for many of these women -- it involved facing fears, overcoming them, and then the payoff -- realizing that the thing they feared most is now the thing that makes them happiest.

"The freedom of being out there is so exhilarating," says Johnson. The way the group's 10 members handle themselves on the road is a metaphor for the relationships that have blossomed among them. They are always looking out for each other, ready to lend a hand and to make sure everyone stays safe.

For Kreinin and Camens, in group after group, the force of these friendships was undeniable. They crisscrossed the country to write the book, and whether the groups were meeting for birthdays or bridge, all the members had found friendships they could count on.

"There's a practical side to being in these groups," says Camens. "Many of us are far from family, so the group can provide extra hands and resources to do whatever is necessary [in a crisis]. Your women's group is your family of choice, in a way."

And such bonds can stand the tests of time and distance, which is why Kreinin stays connected with her New Orleans group, making the pilgrimage to a member's family farm for an extended weekend every year.

"You can commit to the group but take a leave of absence -- there's an unconditional love there. Even when group members scatter, when they get together, they can pick up where they left off."

Camens adds: "It's so valuable to develop a lengthy, common history with other women. It provides a sense of safety, trust and candor. In our group, once a member, always a member -- there's always a seat at the table for you."

Although they encounter a few men's groups in their nationwide search, ultimately they decided that it was a woman thing.

"Women make friendships a priority in a way men don't always seem to," says Kreinin. Camens adds: "The ritual of conversation with women is so important to how we process our feelings. We tend to verbalize, to talk it out instead of just thinking about things internally. [Conversation] is what moves us forward."

The motorcycle-riding Phenomenal Ladies of Prince George's is one of the groups featured in "Girls' Night Out: Celebrating Women's Groups Across America."A.J. Ledbetter, left, and Theoria Johnson of the Phenomenal Ladies. "We have a sisterhood," says Johnson, the group's president. "We just love to ride."