NEW YORK — Sitting on their mothers' laps, six small children wait quietly in a second-floor schoolroom on the Upper East Side. The oldest child is 2; the youngest just turned 1. One sucks his thumb. Another plays with her belly button. Class is about to start.

"Sí, quién está aquí?" asks Verónica Noguera, a youthful teacher with a furry puppet on each hand. "Buenos días, niños. Buenos días."

When Ms. Noguera's tiny students start talking, their first language will be English. But their parents, who don't speak Spanish themselves, have sent their children here to learn what they are sure is becoming an essential skill in this increasingly bilingual city.

"I don't want my child to lag behind," said Linda Hughes, who lives in Cobble Hill, Brooklyn, and commutes an hour each way to take her 3-year-old son, Lucas, to Spanish lessons once a week in Manhattan. "This city is so bilingual already, you can no longer ignore Spanish."

Hispanic New Yorkers Outnumber Every Other Minority

Ignoring Spanish would be quite a feat in New York. Latinos have been woven indelibly into the city's fabric for generations — Puerto Ricans began arriving in the 1930's, followed by Dominicans, Cubans and, lately, Mexicans. Today, half the Bronx's residents are of Hispanic origin; one in five New Yorkers speaks Spanish at home. In the last 10 years alone, the Hispanic presence in the city has grown by 400,000 — the population of Atlanta.

At 2.2 million, Hispanic New Yorkers outnumber every other minority group. While in years past, Hispanic immigrants and Puerto Ricans tended to live and work within the boundaries of traditional enclaves like Washington Heights, the Lower East Side, the Bronx and parts of Queens, today's Hispanic residents are moving beyond the barrios, the factories and the bodegas and are flooding the city's service-oriented businesses looking for work and business opportunities, often in Spanish only.

And non-Hispanic New Yorkers by the thousands, from mothers with babies to office workers, doctors and priests, are responding to the trend in a practical way. They are signing up for Spanish lessons — in their own homes, at work and in night schools. In the last two years, Spanish has become the most requested language in the city's private language schools, where registration has doubled, forcing many schools to add classes or move to bigger buildings, school administrators said.

Knowing Spanish Has Become a Desirable Employment Skill

Speaking Spanish is becoming a desirable skill in the work force, one employers are willing to pay for. Workers in businesses like the St. Regis Hotel, Metropolitan Hospital Center and a variety of news organizations, including The New York Times, have signed up for Spanish classes paid for wholly or in part by their employers. The New York Police Department will soon begin offering language programs to officers. Churches and schools, often unable to fill positions that demand proficiency in Spanish, bring in priests and teachers from Spain and Latin America.

"Thirty years ago, we started training people to do business in Latin America or Spain," said Richard Huarte, director of the New York office of Inlingua, a language school that specializes in corporate accounts. "Now people are learning Spanish to deal with people right here in New York. The Hispanic community is the boom market right now. It's kind of no secret that to reach it you have to know Spanish."

Judy Richler, a former judicial referee on Manhattan's Family Court, knows it well. She realized about three years ago that about a third of the people in her courtroom primarily spoke Spanish. Although interpreters were always available, Ms. Richler said, she decided that to do her job well, she had to be able to match the words to the facial expressions of the people whose fates depended on her rulings.

Ms. Richler signed up for night classes at Cervantes Institute, a language and cultural center near Grand Central Terminal, and joined a tertulia, an evening chat group at the Spanish Institute, a cultural and language center on Park Avenue. Today, Ms. Richler can understand intricate cases and dispense legal advice in Spanish.

"In court, I know what the clients are saying the moment they say it, and they know that I know," said Ms. Richler, 60, who now works as a volunteer lawyer in Housing Court in Manhattan. "The fact that I can look them in the eye as they speak and I see their body language is a great help in what I do."

Spanish Has Replaced English as the Most-Studied Language in New York

Anastasio Sánchez, director of the language program at the Cervantes Institute, said that in the last two years the number of students at his school had almost doubled. Last year, 1,440 students registered for classes; the year before, 850. This year, demand has grown so much that classes are taught in offices and rooms not previously used as classrooms. The school plans to move to a bigger building to accommodate its expanding business.

At the Spanish Institute, about 1,700 students registered for classes last year, double the number of just two years before, even though the school also raised tuition by 10 percent, said Ana Menéndez, the director of the language program.

The number of students taking Spanish in the city's Berlitz language schools has grown by 37 percent. Last year, Spanish surpassed English as the most popular language at one of two Berlitz centers in Manhattan. More than half the students in that center, on Rector Street, said they needed it for work or to move to another job, said Dawn Liles, the school's marketing associate.

The growing interest in Spanish, school administrators said, is a function of how widespread the language has become in New York. Spanish is everywhere these days — from the labels identifying food and produce in the city's busiest supermarkets to the signs on city buses advertising shows on WNJU, Channel 47, the local affiliate of Telemundo, one of the country's two Spanish-language networks.

In the city's schools, Hispanic children make up almost 40 percent of the student body. Many of them are bilingual or know only Spanish. Their growing presence has forced school administrators to scramble before the beginning of recent school years to hire qualified bilingual teachers. Last year, 35 teachers from Puerto Rico and 7 from Spain were hired. This year, 40 came from Puerto Rico and 6 from Spain, school administrators said.

"We'll always have a severe shortage of Spanish teachers. It's an area of great concern to us," said Gary Barton, who oversees teacher hiring for the Board of Education. "Our attempts to bridge that gap are part of every recruitment effort, every advertisement, every speech, everything we do."

In Roman Catholic churches, where Spanish Masses were once rare and confined to basements, about 50 percent of churchgoers are now Hispanic immigrants. The New York Archdiocese has taught Spanish to its priests for decades in its own school. But in the last five years, it has had to bring in 150 priests and 80 nuns from Latin America and Spain, church officials said.

"We've had priests who suddenly realized one day that they were preaching to a group of people who did not understand the sermons," said Martín Poblete, permanent adviser to the Archdiocese on Hispanic affairs.

Businesses and cultural institutions have also taken note of the demographic changes in the city. The 92d Street Y offers health classes and literary events in Spanish. In stores like Harry's Shoes, on the Upper West Side, and the Gap at Madison Avenue and 86th Street, some sales clerks greet clients in Spanish.

"From the top 500 companies to smaller businesses, there is a sense that the Latino population is growing," said Justin Blake, a spokesman with the New York City Partnership and Chamber of Commerce. "The private sector is waking up and seeing that there is an opportunity to make money."

More than 10 percent of the companies that call Blake looking for qualified employees say they want people who speak Spanish, he said. But Spanish is so prevalent in New York that companies can usually find Spanish-speaking employees from the start, he said. Companies and agencies that are based outside Manhattan tend not to seek Spanish lessons because they are able to find a bilingual work force in their own neighborhoods.

Spanish Brings Changes to Churches, Businesses and Municipal Services

In Manhattan, though, language training has become a necessity, especially for people who work in the service industry and in government agencies.

The New York Police Department is now exploring options to offer Spanish classes to all those on the 40,000-officer force who wish to take them. Officials there are meeting with several language schools to design a program for police officers, said Yolanda Jiménez, deputy police commissioner for community affairs.

The interest in Spanish is so widespread that directors at the Cervantes Institute are developing a plan to hold classes at job sites next year instead of having the workers commute to the classes.

Doctors at Metropolitan Hospital Center in East Harlem started taking Spanish lessons at work almost two years ago. A teacher from the Spanish Institute goes to the hospital three times a week. The hospital began offering the classes after administrators at New York Medical College, which staffs the hospital, conducted a survey of patients to find out what language they wished to speak with their doctors. About 65 percent said they would prefer Spanish.

Among the doctors who were taking the course for beginners earlier this year was Dr. George Bousvaros, a 69-year-old cardiologist. He said he trusted that his patients would eventually learn English, but until they do, he wants to be able to ask the type of questions that cardiologists everywhere routinely ask. Dr. Bousvaros has already learned the one word he needs more than any other. It is "corazón," Spanish for "heart."

In the Language Workshop for Children on the Upper East Side, where classes are available for children as young as 6 months, registration has tripled in five years. In 1994, the school had fewer than 50 students learning Spanish; now, there are 180, said François Thibaut, the school's director. A class had to be added this fall to accommodate the increasing demand, he said.

At the end of a recent 45-minute class for toddlers, it was clear that children not old enough to converse in any language already knew the names of fruits — they can pick la manzana verde (the green apple) from a plastic basket — and understand simple concepts like open and closed, high and low, all in Spanish. When asked to pick her favorite color, 2-year-old Alexandrea Duval said "azúl," (blue) to the delight of all.

But perhaps no one was more delighted in that room than Ms. Noguera, Alexandrea's 29-year-old teacher, who is an immigrant from Colombia. Back home, Ms. Noguera was an elementary school grammar teacher. When she came to the United States five years ago, she said, she realized that her English was not good enough for her to continue her career as a teacher.

Then she discovered New Yorkers' thirst for her native language.

"Thank God New York is so Hispanic," Ms. Noguera said. "I can do what I do best, in my own language. I could have never imagined that."