By KIRK SEMPLE

In 1986, when he was 14, Ramiro Carino slipped across the Mexican border and made his way to New York. He moved in with an older sister on 187th Street in Belmont, the neighborhood known as the Little Italy of the Bronx.

Mr. Carino was not quite sure where he had landed: the main language on the street was Italian, that nation’s flag adorned storefronts and homes, and Italian restaurants and shops were everywhere.

Today, the accents of Spanish predominate in Belmont. Mexicans have become a mainstay, working in the shops along Arthur Avenue and inhabiting the surrounding apartments . Some have opened their own businesses, from restaurants to shops selling Mexican Western wear, to stores peddling soccer equipment. Mr. Carino, who survived his early years in the neighborhood by scavenging bottles and, at times, food from garbage cans, started his own enterprise last fall: El Sureno, a small food store and Mexican restaurant.

With three children in public schools, Mr. Carino has not given up his day job cooking at a deli elsewhere in the Bronx. He works there from 6 a.m. to 4 p.m., then returns to his restaurant and cooks until 10 p.m. “I don’t yet feel like a success yet, but I want to triumph,” Mr. Carino said. Then, speaking as much about the gains of his fellow Mexicans in Belmont, he added, “Putting all you got into it, you can triumph.” As the ranks of Mexicans in New York have exploded in recent decades, their impact on neighborhoods where they have settled in the largest numbers has been well documented, like East Harlem, Mott Haven in the South Bronx, and Sunset Park in Brooklyn.

But Belmont offers a glimpse of how Mexicans are gaining a foothold in other parts of the city that are less clearly labeled and where their numbers are far smaller. Slowly and quietly, the neighborhood’s Mexican population appears to have reached the cusp of a breakthrough, injecting new life into the area and challenging old customs. “They sort of snuck up on us,” said Frank Franz, a business leader who has lived all his life in Belmont. “When you saw they had their shops, you said, ‘Wow! They’re here in big numbers.’ ”

It remains unclear whether that budding prosperity will translate into real political and economic power ? a question with big implications for a city in which Mexicans are now the fastestgrowing major immigrant group. In 1980, 35 people of Mexican descent lived in Belmont, according to calculations based on census data from the sociology department of Queens College in New York.

By 2008, they had grown to more than 3,200, or about 14 percent of the population. That parallels an increase in Mexicans across the city ? according to the Census Bureau, to more than 170,000 today from about 6,700 in 1980 ? driven by immigration and a high birthrate. In Belmont, the population surge has been felt in schools and churches.

At the Roman Catholic Church of Our Savior, Mexicans now make up about 80 percent of the congregation, staff members said. At Public School 32, about a quarter of the student body is of Mexican descent, administrators estimate.

At Our Lady of Mount Carmel Church, the Roman Catholic parish in Little Italy, Masses said in Spanish were added after first meeting resistance from Italian parishioners accustomed to Mass in English and Italian.

“I think they’ve accepted the situation,” said Sister Martina San Pedro, who was brought by the New York archdiocese from Mexico 14 years ago to work with Latino parishioners at Mount Carmel. “I guess they have realized that things have escaped from their hands and they have to accept it.”

Mr. Franz, the business leader, has already seen plenty of evidence of Mexicans putting down roots in Belmont. Four years ago, he said, after Mexico had been eliminated from the World Cup in an earlier round and Italy had won, Mexicans ran down the streets with an Italian flag, cheering, “We won!” Old-timers took note, and it helped bond the two populations, Mr. Franz said.

“I think the way they see it was, ‘Yeah, we’d like to see Mexico win, but if Mexico can’t win, we’d like to see Italy win, because we’re part of Little Italy.’ They’re here to make it their home as we made it our home.” As is the case in many New York neighborhoods, Mexicans have not yet become active in business associations in Belmont. Still politically inchoate, they lack leaders. Mr. Franz said he hoped Mexicans would emerge to help steer development. “We’re really trying to incorporate everyone as a neighborhood,” he said.