This is a book about adultery. If you're American and you don't read on, I'll understand why. Adultery provokes more outrage in America than in almost any other country on record (Ireland and the Philippines are two exceptions). When I mention cheating to Americans, they usually stare at me for a few seconds, trying to sort out whether they're guilty of anything or wondering if I'm propositioning them. A few launch into rants about the importance of monogamy. Some spontaneously confess at the mere mention of infidelity.

I started seriously thinking about affairs when I was posted to Latin America for the Wall Street Journal. For the first time in my life, married men routinely tried to sleep with me. It wasn't, unfortunately, that I had suddenly become irresistible; many of my female friends reported similar advances. Even when these "suitors" were otherwise appealing, I found their offers repugnant. What about their obligations to their wives? I also interpreted the come-ons as personal slights. Did I seem so desperate that I'd settle for being the proverbial other woman? At the time, I was single, newly thirty, and in the market for a husband of my own...

I was intrigued, and wanted to know more about the rules of infidelity around the world. But as I started poking around, I saw that there was no easy way to discover them in America or anyplace else...

The only way to find out how people around the world cheat is to ask them. So I did. I visited two dozen cities in ten countries. Along the way I read advice columns, personal ads, and newspaper accounts of affairs in many languages, and interviewed leading historians, psychologists, and sexologists. Wherever there was academic research on affairs, I combed through that, too.

And, of course, I interviewed scores of adulterers and their mates. To my amazement, although I was a stranger showing up with a voice recorder and a promise to change their names (I did, along with some identifying details), people around the world told me their sexual secrets. By the time I left town, I was usually turning people away...

America was different. Nearly all the people I interviewed said they hoped that by telling their stories they'd help someone else. Americans of every walk of life and political persuasion said this... Outside America no one said anything remotely like this. It didn't occur to them that talking about affairs might be an act of public service...

This book doesn't ask whether we're genetically programmed to cheat or whether cheating has evolutionary benefits. I assume that people everywhere have roughly the same mix of biological urges. I want to know how people in different cultures channel those urges...

Excerpted from Lust in Translation by Pamela Druckerman, published in May 2007 by The Penguin Press, a member of Penguin Group (USA) Inc.; © Pamela Druckerman, 2007.