SHEFFIELD, England — The downtown streets with their Georgian row houses and Victorian clock towers have names that have long been thought of as typically British — Queen, Wellington, Duke, Bank, Castle.

The shops and storefronts nestled among them have names that are fast becoming typically British — Marcia's Caribbean Takeaway, Imran's Southern Fried Chicken, the Kebab House, the Somalian and Mediterranean Food Hall.

But the 40,000 nonwhite residents of this city of 530,000 in the heart of Britain, many of them born and raised here and speaking in the distinctive broad vowels of a Yorkshire accent, identify themselves as anything but British. They do not even say Afro-British; it's Afro-Caribbean — not Asian-British, simply Asian.

This self-definition strikes a nerve in Britain, where the government has made taking on a common sense of British nationhood by the immigrant population a critical measure of progress in its push for racial integration and assimilation.

Experience in cities like Sheffield proves that it is one thing to transform churches into mosques, tea rooms into curry houses and old depots and cutlery workshops into ethnic community centers and something else again to turn people who feel foreign into self-proclaiming Britons.

"The only times I call myself British are when I go to get a passport and when someone asks me where my accent comes from," said Jenni I'Anson, 33, a mental health aide of Jamaican parentage who was born in Sheffield. "Otherwise I would never class myself as British. There is no sense of belonging here. I would only say that I am African-Caribbean."

Her nephew, Theo Hamilton, 15, a third-generation Sheffielder, said, "British to me means white, and I don't get treated like a white person, so I don't think of myself as British."

European countries are experiencing profound changes in their population mixes, and Britain's reputation as one of the region's more stable multiethnic societies was shaken during the summer by a series of riots in cities with substantial immigrant populations.

In the aftermath of Sept. 11, the country also found that it had been a breeding ground for young Islamic radicals linked to terror groups and committed to holy war against the West.

According to the Office of National Statistics, Britain is 7.1 percent nonwhite, with 2.2 percent of the population categorized as black, 3.4 percent from the Asian subcontinent and 1.5 percent Chinese and "other groups."

Of the 82,000 people granted British citizenship in 2000, 27 percent were from Asia, 35 percent from Africa and the Caribbean and 8 percent from the Middle East.

A government report on the summer outbreaks concluded that whites and ethnic minorities in Britain were leading separate lives with no social or cultural contact and no sense of shared nationality. It urged immigrants to become active British citizens.

In February, Home Secretary David Blunkett recommended that minorities speed the process of integration by adopting British "norms of acceptability," and he proposed that newcomers take an oath of allegiance, study British history and culture and embrace "our laws, our values, our institutions."

Sheffield, England's fourth-largest city, would seem to be a place where that project would enjoy more success than elsewhere in Britain. Race relations have been less combative here than in cities like London, Birmingham, Liverpool, Bradford and Leeds with histories of rioting.

The local government has been more attentive and the police more communicative. "Here we do it better," said Mohamed Awale, 56, a development worker of Somali background who came here in 1994. "It's not so explosive."

But even nonwhite people in Sheffield who have had success in getting educations, finding jobs and building stable lives say they still do not feel they are part of the same nation inhabited by white residents, and they resent the official entreaty to think otherwise.

"Of course it's the wrong thing to be asking of us," said Zahid Hamid, 46, who came here from Pakistan in the early 1960's. "What a lot of so-called English want us to want is leafy Oxfordshire.

"But what we want is a job, a decent place to live, safety, a chance to educate our children. We want to preserve our separate identities. And remember, we must still also maintain the economic link with our original homes. Forty years later, I am still sending money back."

Britain's policy had been one of championing multiculturalism, an approach that seeks to guarantee equality of opportunity while respecting and even celebrating cultural differences.

Many nonwhites in Britain thought they witnessed a departure from that ideal with the publication of the report and the subsequent recommendations of citizenship classes and pledges. They reacted with bewilderment and anger.

"You can't give your allegiance to a country that is trying to exclude you," said Seaton Gosling, 63, the Jamaican-born chairman of Sheffield's Black Community Forum. "Everyone wants to keep the right to preserve his culture and identity."

The exclusion that arouses their anger is the barrier they feel white society places in the way of job advancement. "I have a Ph.D., and I find it impossible to get past a certain level," said Abdul Shaif, 40, an education officer with the City Council who came here in 1971 from Yemen. "Not one black manager has made it onto the ladder."

Uttering a lament common to minority workers in immigrant societies, Raja Shaffique, 44, a Pakistani-born housing officer, said, "We have to be twice as good as our white colleagues to get the same job."

While Sheffield, like other British cities, has largely segregated residential patterns, that form of separation upsets minority residents less than the blockage in workplace advancement. For many of them integration appears to be less of a goal than it is for the government.

"Even after 40 years here, I like to see a black face close by," said Mr. Gosling of his Afro-Caribbean neighborhood. "It's a kind of comfort. But I have to add that if society had shown us years ago that it wanted us, it wouldn't have driven us into this kind of protectiveness."

Ms. I'Anson said young people were even less interested in integration. "The young generation is more segregated than we were," she said. "They're more aware of the issues." She said she recently gathered a group of black youths to try to interest them in a job that had come up. "Do you know what the first question always was?" she asked. " `Is the boss black or white?' "

Her nephew Theo said the only white people he ever encountered were police officers who regularly stopped him on the street. "I don't know any white kids, but I try to mingle with them so I won't get picked up so much," he added.

Isadora Aiken, 50, a Jamaican-born business manager who came here in 1967, said: "People are simply not integrating. I go out onto the High Street and into the downtown department stores, and black people are not visible there at all."

Mr. Shaif protested the imperative the government was putting on integration. He said a teenager he had a conversation with days earlier explained the quandary of being Asian and British at the same time. "By day I'm English," she said. "But at night I'm Yemeni."

Angela Baugh, a 39-year-old filmmaker of Jamaican background, and her two children were born here. "I am second generation and the mother of the third, and none of us say we're British."

She said she was reminded of her outsider status every time she came back to Britain from abroad and went through customs. "When I go into the European Community line, I'm stopped and quizzed and made to feel like I'm either an asylum seeker or a refugee," she said. "So how am I expected to ever feel British.?"