JEFFREY BROWN:Next: abandoning a widespread and painful rite of passage.

Special correspondent Fred de Sam Lazaro visited the West African nation of Senegal. His report is part of our Agents for Change series.

And a note: Some viewers may find the subject matter troubling.

FRED DE SAM LAZARO:As dusk approaches, a group called Tostan sets up a giant screen in this remote village in Senegal. To overcome language barriers, the feature will be a 1929 Buster Keaton silent film. The film is a hit, as were events put on earlier in the day by Tostan.

Its mission is to teach about human rights, specifically the right to health, but its seminars and skits will often lead to a discussion of an age-old custom: female genital cutting.

WOMAN:She needs to be cut. All girls need that. You can't have a recognized marriage if she's not cut.

FRED DE SAM LAZARO:This painful rite of passage is practiced by both Muslims and Christians across a swathe of mostly African nations, from Senegal to Egypt.

Each year, the World Health Organization says up to three million girls in Africa are subjected to genital mutilation, and up to 140 million women live with its consequences. Genital cutting probably originated in the harems of ancient rulers as a means of controlling women's fidelity, or a sign of chastity among those who aspired to be consorts, according to Molly Melching, who started Tostan.

MOLLY MELCHING,Founder, Tostan: As the years went on, I mean, 2,220 years, it became very much a part of what was considered criteria for good marriage.

FRED DE SAM LAZARO:Melching is an Illinois native who has lived here for about four decades, first as a student, then a Peace Corps worker.

Genital cutting was rarely discussed publicly, and in fact when she began Tostan 20 years ago, her goal wasn't to end it, but instead to simply provide information that was sorely lacking.

MOLLY MELCHING:When you see a friend that you've known for several months and you've gone to her house for lunch, and then she tells you her child has some problem, that it's someone who has cast an evil spell on the child, the baby, and that she's going to take them to a religious leader to get the spell taken off, and you don't know what to say, and it turns out the baby was dehydrated.

FRED DE SAM LAZARO:But the more Tostan's staff and volunteers talked to local communities about health, the more the topic Melching calls FGC came up, since people began to tie it to bad health.

MOLLY MELCHING:So, suddenly, as they started learning germ transmission and the consequences of FGC and how these infections occur and why they had more problems in childbirth than other women who have not been cut, they started saying, wait a minute.

FRED DE SAM LAZARO:To go from talking about an age-old cultural norm to actually changing it presented a huge challenge. Tostan's approach has been to go to local imams to get their agreement that the ritual is not a religious obligation.

MOLLY MELCHING:We share our modules with the religious leaders, so that they see that everything that we do is for the well-being of the community, the health, and all these things are things that Islam espouses. And so they're very happy in general, but first of all they're happy because we start with them.

FRED DE SAM LAZARO:That respect also carries over into the group's messages in general.

MOLLY MELCHING:Tostan found that using approaches that shame or blame people really was just the opposite of what would work in changing social norms.

When you say to someone, we know you love your daughter and you're doing things because you love your daughter, but let's look at this and let's try to understand together exactly what are the consequences of this practice, but you are the ones that will have to make the decision, then suddenly people are willing to listen. They don't get defensive.

FRED DE SAM LAZARO:It's been far more effective than the approach of many aid groups, says University of California, San Diego, Professor Gerry Mackie.

GERRY MACKIE, University of California, San Diego: When we think of an ideal way of making a change, we'd say it's democratic. We all get together and talk it over and decide what the best thing is to do, whereas some development approaches would, say, force them to do it, pay them to do it, trick them into doing it.

FRED DE SAM LAZARO:In Tostan's approach, local leaders and elders produce the skits and lead discussions. Their words and personal experience carry strong credibility.

Diarre Ba used to make a living as a cutter.

DIARRE BA, Senegal: I was part of this process. I felt bad. This is not right. But I didn't know anything at the time. I had no learning.

MARIAM BAMBA, Senegal: It's painful. I can never forget the pain, so painful.

FRED DE SAM LAZARO:Mariam Bamba is a longtime campaigner for Tostan, and she spared her 10-year-old daughter the trauma. Yet, early in her own marriage, she was determined to keep up the tradition, even though her own husband was opposed to it.

SULEYMAN TRAORE, Senegal: She insisted that she had to do it. There were so many problems if you didn't do it. If you cooked meals, no one would eat your food. It's because we didn't know.

People told us that it was our religion. If you don't do it, you'll be going against your religion. All this is false. But I alone can't do this in the village.

FRED DE SAM LAZARO:Doing this alone could render one's daughters unmarriageable.

So one of Tostan's most critical roles today is to lessen the stigma by getting whole communities and others into which they might marry to jointly declare an end to cutting. Public rallies called declarations have increased to include hundreds of villages who gather to celebrate the decision.

GERRY MACKIE:One part of bringing about a change like this is to get everyone to change at once, what we call coordinated abandonment. Everyone has to see that everyone else sees that everyone is changing.

MOLLY MELCHING:Never in my wildest dreams could I have imagined that I would be sitting here years later, saying that 4,792 communities in Senegal had abandoned. In the beginning, it was just unthought of, unbelievable, because it was so taboo.

FRED DE SAM LAZARO:Since our visit, the number of communities has grown to more than 5,000, and many have also pledged to change another tradition, the frequent practice of allowing older men to marry adolescent girls, acknowledging both the health risks and the girls' human rights.

Molly Melching says there are examples in history of this kind of sweeping shift in social norms and attitudes. She sees a very current one every time she comes home in American views on smoking.

MOLLY MELCHING:People were smoking, and nobody said anything about it much through the '50s, the '60s, and even the '70s. And as people became more and more aware of the harm that it causes, more and more people -- there was a critical mass of people who started really protesting. It was amazing for me, coming from Senegal to the United States, to see how quickly things turned around.

FRED DE SAM LAZARO:Tostan's efforts have now expanded beyond Senegal to seven other African nations.

JUDY WOODRUFF:A version of Fred's story aired on the PBS program "Religion & Ethics Newsweekly."

His reporting is a partnership with the Under-Told Stories Project at Saint Mary's University in Minnesota. He talks more with Molly Melching on our World page. Find their conversation about how she got her start in activism against genital mutilation.