After school and before prayer class, 12-year-old Raniey Arief waited impatiently next to a bodega on Cortelyou Road as a Moroccan schoolmate ran in. Inside, two cashiers, one Cuban and the other Tibetan, waved as her friend scampered to grab a raspberry juice.

This type of cultural mishmash is the norm for Raniey, who wore a traditional Pakistani scarf and skirt with a leopard skin print. Her friends hail from such far-off places as Haiti, Russia, Italy, Mexico, and Poland. “It’s fun,” Raniey said. “They teach you different languages.”

According to certain measures of U.S. Census data, the most diverse area in the nation is the Cortelyou Road section of Ditmas Park, a swath of Brooklyn’s Victorian Flatbush where home values have skyrocketed in recent years.

A neighborhood south of Prospect Park where 100-year-old mansions sit next to working-class apartment buildings, Ditmas Park’s population has undergone a sea change since 1970, when the area was almost entirely white.

The shift came gradually, reflecting the increased diversification of immigration to New York after the liberalization of federal immigration laws and white out-migration to the suburbs.

In 1970, Census Tract 520 in Ditmas Park was 92.1% white. Less than a quarter of the population was foreign-born, and most of them were Italian and Jewish. Today, the neighborhood is a miniature United Nations, with nearly two-thirds of the population coming from other countries.

Although Elmhurst and Jackson Heights have a larger percentage of foreign-born residents, the city’s demographer, Joseph Salvo, said it’s the convergence of racial and ethnic diversity that distinguishes Ditmas Park.

The neighborhood owes much of this diversity to its location and unique housing mix. Cortelyou Road is the focal point for a number of burgeoning ethnic communities, and the Q line running through it provides a central axis. Mr. Salvo likened the neighborhood to the Four Corners area in the Southwest, where Arizona, New Mexico, Colorado, and Utah meet.

Gabriel Carugno has been watching the changes in the neighborhood over the past few decades from his perch at Gabe’s Camera City & Video on Cortelyou Road.

“It happened very, very slowly,” he said. Twenty-five years ago, Afro-Caribbeans from Flatbush began to move to Ditmas Park, and Orthodox Jews began to overflow from Boro Park. Later, Mexicans and other Hispanic groups moved in, opening their own ethnic grocery stores. When Pakistanis started to flood into the neighborhood, a mosque opened up down the street. More recently, “young folks from Greenpoint and Williamsburg, artist types,” joined the neighborhood, he said.

“The mix is unbelievable,” said Mr. Carugno, whose store has served the community for 49 years. “You’ve got everything you can think of.”

The diversity in Ditmas Park and the larger neighborhood of Victorian Flatbush, of which it is a part, may have reached its peak, however. As more white professionals with children move in to the area’s six-bedroom mansions from Park Slope, Lower Manhattan, and the Upper West Side, the neighborhood is “definitely gentrifying,” said longtime real estate agent Mary Kay Gallagher. The large homes, which are now selling for $1 million and up, provide an almost New England-style charm in the middle of the city. At the same time, the nearby co-ops are also increasingly attracting young white professionals.

“It’s been a sleepy community and all of a sudden we’ve been discovered,” Ms. Gallagher said. No longer, does she have to convince home-hunters to look beyond Prospect Park. “The prices just keep going up,” she said, driven by the quality of the houses, the diverse community, easy access to the Q line, and the opening of more stores and restaurants.

Mr. Carugno pointed to Vox Pop, a cafe further down Cortelyou that advertises itself as “Books, Coffee, and Democracy,” as symbolic of the new wave. It offers wireless Internet access and a play area for toddlers, as well as vanilla lattes.

One of the owners of Vox Pop, Sander Hicks, said they recognize they have “been criticized for potentially being gentrifiers” since the cafe opened last fall. But they are striving to find ways to “not be an elite bohemian niche in the neighborhood.”

The neighborhood, like much of Flatbush, has recovered from its low point in 1977, when arsonists were hired by landlords looking to pocket the insurance money for properties that had depreciated when many of the white tenants left. Now that the neighborhood has begun attracting middle-class, mainly white tenants, however, the potential for tension exists.

“As we develop economically we don’t want to lose the diversity, and so far we don’t see that happening, “the executive director of the Flatbush Development Corporation, Susan Siegel, said.

“We have everything from Section 8 to people living in million-dollar homes in the same catchment area. It is a melting pot certainly,” Ms. Siegel said, adding that on her street alone she has neighbors who are Pakistani, Barbadian, Jewish, Israeli, Mexican, Russian, Serbo-Croatian, and African. Still, while many communities live side by side, there is not always contact across groups. “There is room for more interaction and integration within the ethnic groups,” she said.

Indeed, despite the diversity, not everybody feels like part of a broader community. After prayer class recently, Raniey ran into a family friend, Husan Sutan, greeting him in a dialect of Urdu.

While Raniey’s friends are from all over the world, Mr. Sutan said life for him in the country’s most diverse neighborhood was much like in his home country: He only socializes with Pakistanis.

“They can go to the school,” Mr. Sutan said of Raniey and her diverse group of friends. “I’m just a taxi driver.”