Shiho Fukada for The New York Times

Aminata Kante left her husband after he took a second wife.

SHE worked at the Red Lobster in Times Square and lived with her husband near Yankee Stadium. Yet one night, returning home from her job, Odine D. discovered that African custom, not American law, held sway over her marriage.

A strange woman was sitting in the living room, and Ms. D.’s husband, a security guard born in Ghana, introduced her as his other wife.

Devastated, Ms. D., a Guinean immigrant who insisted that her last name be withheld, said she protested: “I can’t live with the woman in my house — we have only two bedrooms.” Her husband cited Islamic precepts allowing a man to have up to four wives, and told her to get used to it. And she tried to obey.

Polygamy in America, outlawed in every state but rarely prosecuted, has long been associated with Mormon splinter groups out West, not immigrants in New York. But a fatal fire in a row house in the Bronx on March 7 revealed its presence here, in a world very different from the suburban Utah setting of “Big Love,” the HBO series about polygamists next door.

The city’s mourning for the dead — a woman and nine children in two families from Mali — has been followed by a hushed double take at the domestic arrangements described by relatives: Moussa Magassa, the Mali-born American citizen who owned the house and was the father of five children who perished, had two wives in the home, on different floors. Both survived.

No one knows how prevalent polygamy is in New York. Those who practice it have cause to keep it secret: under immigration law, polygamy is grounds for exclusion from the United States. Under state law, bigamy can be punished by up to four years in prison,

No agency is known to collect data on polygamous unions, which typically take shape over time and under the radar, often with religious ceremonies overseas and a visitor’s visa for the wife, arranged by other relatives. Some men have one wife in the United States and others abroad.

But the Magassas clearly are not an isolated case. Immigration to New York and other American cities has soared from places where polygamy is lawful and widespread, especially from West African countries like Mali, where demographic surveys show that 43 percent of women are in polygamous marriages.

And the picture that emerges from dozens of interviews with African immigrants, officials and scholars of polygamy is of a clandestine practice that probably involves thousands of New Yorkers.

“It’s difficult, but one accepts it because it’s our religion,” said Doussou Traoré, 52, president of an association of Malian women in New York, who married an older man with two other wives who remain in Mali. “Our mothers accepted it. Our grandmothers accepted it. Why not us?”

Other women spoke bitterly of polygamy. They said their participation was dictated by an African culture of female subjugation and linked polygamy to female genital cutting and domestic violence. That view is echoed by most research on plural marriages, including studies of West African immigrants in France, where the government estimates that 120,000 people live in 20,000 polygamous families.

“The woman is in effect the slave of the man,” said a stylish Guinean businesswoman in her 40s who, like many women interviewed in Harlem and the Bronx, spoke on the condition of anonymity. “If you protest, your husband will hit you, and if you call the police, he’s going to divorce you, and the whole community will scorn you.”

“Even me,” she added. “My husband went to find another wife in Africa, and he has the right to do that. They tell you nothing, until one afternoon he says, ‘O.K., your co-wife arrives this evening.’ ”

Men, in contrast, tended to play down the existence of polygamy, if they were willing to discuss it at all.

Dr. Ousseiny Coulibaly, 36, a gynecologist, was born in Mali and educated in France, where polygamy has long been an explosive immigration and women’s rights issue. Yet he said he was unaware of any cases among his West African patients at Harlem Hospital Center.

“I’m not asking,” he said. “I’m not even suspecting it. There might be so many things I don’t know.”

Don’t-ask-don’t-know policies prevail in many agencies that deal with immigrant families in New York, perhaps because there is no framework for addressing polygamy in a city that prides itself on tolerance of religious, cultural and sexual differences — and on support for human rights and equality.

Last summer, when a nonprofit agency in the Bronx surveyed the needs of the sub-Saharan immigrants in its child care and literacy programs, questionnaires asked about interest in marriage counseling, but not about polygamy.

“This is a very private community,” said Rose Rivera, director of Head Start at the agency, the Women’s Housing and Employment Development Corporation, which largely relies on the fathers to translate for the mothers. “They’re not really ready to trust us.”

Yet on Monday, two Gambian women with children in the program acknowledged, when asked by a reporter, that polygamy was a given in their lives. Both described themselves as “first wives,” married at 16, who joined their husbands in New York in the 1990s, never having attended school.

One, now 36, with three children, said her husband was betrothed to a second wife in Gambia whom he would soon bring to the Bronx. Protest was pointless. “They won’t listen,” she said. “Whether you like it or not, they will marry.”

Islam is often cited as the authority that allows polygamy. But in Africa, the practice is a cultural tradition that crosses religious lines, while some Muslim lands elsewhere sharply restrict it. The Koran says a man should not take more than one wife if he cannot treat them all equally — a very high bar, many Muslims say.

Ms. Traoré, of the Malian women’s group, cited two prosperous households in Bergen County, in New Jersey, that seemed to pass the test.

“They get along very well,” she said of the wives in one home, who married their husband in Africa at the same time. “It’s extraordinary. When they come to our celebrations they dress the same, the same outfit, the same jewels. The husband is completely fair.”

Still, since only one wife could have entered the country as a spouse, the other is probably more vulnerable to deportation, she acknowledged.

More typical, many immigrants said, are cramped apartments in the Bronx with many children underfoot, clashes between jealous co-wives and domestic violence. And if the household breaks up, the wives’ legal status is murky at best, with little case law to guide decisions on marital property or benefits.

Men, too, can end up in polygamous marriages reluctantly, driven by the dictates of clan and culture. That seems to be the case for the husband of Ms. D., the Guinean restaurant worker. Efforts to reach him for this article failed, but as Ms. D. tells it, he insisted he was just as surprised as she was when his first wife, left behind in Ghana, showed up six years ago.

Their match, like many African marriages, had been made by their families before he left for New York. Years later, he met and courted Ms. D. in the Bronx, saying his relationship with his Ghanaian wife was over.

But a year after he married Ms. D. in Guinea and they returned to the Bronx, relatives arranged for a visa for his first wife to join them. “In Africa, women accept things like that,” Ms. D. said. “Here, the apartments are too small.”

She recalled terrible fights during the three months they all lived together. The conflicts continued after she paid for the first wife to move to another apartment. For eight months, the husband shuttled between the two, but he became abusive, she said. And when Ms. D was five months pregnant, he stopped showing up.

Like many West African women, Ms. D. had been subjected to genital cutting as a child, making sex painful. The other wife had not been cut.

“It’s not life, your man sharing a bed with another woman,” Ms. D. said. “You’re always thinking in your head, ‘does he love me?’ ”

Such stories of polygamy, New York style, are typically shared by women only in whispered conversations in laundries and at hair-braiding salons. With no legal immigration status and no right to asylum from polygamy, many are afraid to expose their husbands to arrest or deportation, which could dishonor and impoverish their families here and in Africa.

But Aminata Kante, an immigrant from Ivory Coast who found help for herself and Ms. D. at Sanctuary for Families, an agency for battered women, uses her own story to urge rebellion.

Wed at 15 in Ivory Coast, over the telephone, to a New York City taxi driver thousands of miles away, Ms. Kante was delivered to her groom on a false passport. She said she endured his abuse for years, bore three children, turned over her paycheck from work as a health aide, and tried harder to appease him when he sent two of the children to Africa.

But something snapped, she said, when he announced that he had taken a teenage second wife, also married, just as she had been, over the phone — a valid wedding in Ivory Coast. Ms. Kante left him.

Relatives pressed her to return. Uncles warned that she would be branded a bad woman, and that the stigma would follow her children in Africa. Without papers, vulnerable to deportation, she ended up in a homeless shelter.

But now, at 30, she tells the story in the warm glow of her own living room, her children restored to her, and a green card secured, through unusual legal efforts by lawyers at Sanctuary.

“I know a lady who lives with her husband and another woman in one room, a two-bedroom, with 11 kids,” she said. “I tell her, she has to move — it’s not a life.” And her own husband? His second wife is 23 now, with three children.

And recently, Ms. Kante said, he married a third.

Copyright 2007 The New York Times Company. Reprinted from The New York Times, New York Region, of Friday, March 23, 2007.