Deborah Tannen, a professor of linguistics at Georgetown University, has written one of the hottest books of the summer. "You Just Don't Understand," goes a long way toward explaining why perfectly wonderful men and women behave in ways that baffle their partners. People are telling Tannen that the book is saving their marriages.

What she is saying is that men and women grow up behaving in such profoundly different ways, and seeing themselves connecting to others in such profoundly different ways, that the two sexes are really trying to communicate across two different cultures. Because most of us don't understand that, however, we think that our particular partner is the only one who is weird and problematical.

Men, she writes, are socialized as little boys to play in groups in which there is a leader and followers. "It is by giving orders and making them stick that high status is negotiated. Another way boys achieve status is to take center stages by telling stories and jokes.

"Girls, on the other hand, play in small groups or in pairs; the center of a girl's social life is a best friend. Within the group, intimacy is key."

These two very different styles produce entirely different adults. Tannen writes of her own husband that he "frequently seemed to see others as adversaries when I didn't."

Sound familiar?

"I now see that my husband was simply engaging the world in a way that many men do: as an individual in a hierarchical social order in which he was either one-up or one-down. In this world, conversations are negotiations

in which people try to achieve and maintain the upper hand if they can,

and protect themselves from others' attempts to put them down and push them around. Life, then, is a contest, a struggle to preserve independence and avoid failure.

"I, on the other hand, was approaching the world as many women do: as an individual in a network of connections. In this world, conversations are negotiations for closeness in which people try to seek and give confirmation and support, and to reach consensus . . . . Though there are hierarchies in this world too, they are hierarchies more of friendship than of power and accomplishment."

"Though all humans need both intimacy and independence, women tend to focus on the first and men on the second. It is as if their lifeblood ran in different directions."

Nowhere is this played out more constantly than in the way we converse with each other. Thus, women frequently complain about how men react when they are discussing trouble, and the man reacts by giving them a solution. "A lot of men go back to saying, well, why does she ask for my advice when she doesn't want it?" says Tannen. "It's hard for them to grasp the idea that a woman would want to simply talk -- that talking is what she's after."

Then there is the classic situation of a man refusing to ask directions and driving around, getting hopelessly lost, while the wife sits in the car, fuming. "It has blown my mind how many people -- men and women -- have responded to that," says Tannen. In the book, she explains what is really going on. It is not, as women have assumed across the ages, merely a matter of the man being stubborn.

"The fact that you have the information, and the person you are speaking to doesn't, also sends a metamessage of superiority," she writes. "If relations are inherently hierarchical, then the one who has more information is framed as higher up on the ladder . . . . From this perspective, finding one's own way is an essential part of the independence that men perceive to be a prerequisite for self-respect. If self-respect is bought at the cost of a few extra minutes of travel time, it is well worth the price."

The husband will say that the person on the street won't know the directions, anyway, so why ask because he'll give wrong information. (This is all sounding very familiar, isn't it?)

The wife disagrees, because in her culture the person would simply say, "I don't know." In the husband's culture, that admission would be intolerably humiliating, so he assumes the person would take a wild guess.

Tannen says her mother, married 57 years, read her bestseller last week. "She said, 'I couldn't believe it. You mean it's not just Daddy? I always thought he was the only one.'

"If you don't know there are differences, you don't want to make adjustments. You think you are doing it the right way and the other person is doing it the wrong way. If your partner is accusing you, then you certainly don't want to make any change, because that would be admitting you are wrong. But when you lift the blame off it, then people find their own ways to make adjusments."

And the good news, as she puts it, is that they want to.