The aggressive program of the schools chancellor, Joel Klein, to attract new charter schools to the five boroughs is paying off.

This fall, the Department of Education received 40 applications from groups hoping to open charter schools next September. That’s more than triple the number of applications received last year.

“Our efforts to stimulate supply in New York City are paying off, and talented educators and entrepreneurs are applying,” the director of new schools, Kristen Kane, said.

She attributed the rise in applications for charter schools to the city’s policy of providing building space for new charter schools and to the city’s Center for Charter School Excellence, which helps organizations interested in opening charter schools complete the rigorous application process. Ms. Kane also credited the chancellor, who, she said, “believes that charters can and should be an important part of the overall public education reform strategy in New York City.”

This year, the city opened eight new charter schools, which are publicly financed but not subject to the same rules and regulations as traditional schools.

A spokeswoman for the education department, Michele McManus, said next fall might see approximately 15 new charter schools.

Four of the applicants, including Amistad Academy, already operate successful schools outside New York City.

Three groups already operate schools in New York City and want to expand.

One public school is converting into a charter school.

The remaining applications are from new groups looking to hop into the charter-school movement for the first time.

While local and national applicants are approaching city officials, the department is also reaching out to some potential applicants.

For example, Mr. Klein approached the Knowledge is Power Program, which already operates one school in the Bronx and one in Harlem, and Amistad Academy, which operates one school in New Haven, and actively encouraged them to consider expanding in New York City.

Most of the planners of new schools are hoping to open in 2005, Ms. Mc-Manus said, but some might decide to wait until 2006.

The United Federation of Teachers, which has been talking about starting a union-run charter school, missed this fall’s deadline because it hasn’t yet won approval from its delegate assembly or completed the lengthy application. That means the soonest the teachers union could open a charter school would be September 2006.

Before the charter schools can open their doors, they must undergo a rigorous review process. First, they must win approval from the city’s education department. Those that pass that phase are sent to the state Education Department for review. The state recommends the schools it likes to the Board of Regents, which ultimately decides.

The vice president of the Charter School Resource Center, Peter Murphy, called the number of new applicants “substantial” and said it’s not surprising.

“This chancellor has made it clear that he wants to do these,” Mr. Murphy said. “When an authorizer publicizes the fact that he’s open to business, people are attracted to that.”

He said the high volume is “a sign of the demand in the city by parents.”

The president of the New York Charter Schools Association, Bill Phillips, said the high level of interest in starting up new charter schools is a sign that the state Legislature should remove the cap on new charter schools.

Under current law, New York can authorize no more than 100 charter schools. The Board of Regents, which authorizes all of the city-approved charter schools, has 22 slots left. If it granted 15 in New York City and the four outstanding in Buffalo, it would be dangerously close to the limit, Mr. Phillips said, adding that the State University of New York also only has a few charters to dispense.

Mr. Klein “was absolutely right” in portraying the cap on charter schools as an obstacle to progress, Mr. Phillips said. He referred to the chancellor’s statement to the special masters in the Campaign for Fiscal Equity’s victorious court battle to win more resources for the city’s schools.

“Let’s hope that the Legislature hears that message too,” Mr. Phillips said.

It’s no surprise, he said, that demand for charter schools is so high. He said the Bronx has 23,000 students in charter schools and 24,000 on waiting lists.

Mr. Phillips said the city should approve as many of the schools as it can, while still respecting the high bar that state law sets for granting charters. He also said some of the groups that want to establish new schools might choose to spend an extra year preparing.

“It’s like good wine,” he said. “You don’t want to have it before its time.”