New York City education officials plan to overhaul as many as two-thirds of the city's 218 middle schools, eliminating many of them, as part of a major effort to improve schooling for young adolescents.

In place of the middle schools, officials plan to recreate old-style kindergarten-through-eighth-grade grammar schools and open new high schools for the 6th to 12th grades.

The junior high school grades have long been regarded as the most difficult years of schooling, a time when puberty and social pressures pose enormous obstacles to effective instruction. About half the city's middle schools have been designated by the federal government as "in need of improvement."

Officials said that up to three dozen of the new schools would be in place by September, but that many conversions would have to await the construction of new buildings over the next five years.

"We are developing a multiyear comprehensive plan," said Michele Cahill, senior counselor for educational policy to Schools Chancellor Joel I. Klein. "We are looking as soon as September 2004 to have more configurations that we think improve continuity and improve student-teacher connectedness."

But Ms. Cahill hastened to add that school configurations were only one aspect of a wider effort that would include changes to curriculum, the organization of the school day and student support services. "The overarching goal is really to strengthen middle-grades education," she said.

Among the changes would be greater personal attention for students and a number of new strategies that would include, for instance, the same math teacher following students from grade to grade.

New York is not alone in searching for innovative approaches. Many other districts across the nation have reinstituted kindergarten-to-eighth-grade schools, but few have experimented with the 6th-to-12th grade configuration.

But not all experts think that eliminating stand-alone middle schools is a cure-all. "Grade configuration in and of itself is not the magic bullet we are looking for," said Sue Swaim, the executive director of the National Association of Middle Schools.

"If we are not paying attention to what we know is appropriate for young adolescent learners, no matter what the grade configuration, we are not going to be making the progress that we need to be making," Ms. Swaim said. "They are not larger versions of elementary kids or smaller versions of high school kids. They are a unique age group."

James A. Kadamus, deputy New York State education commissioner, said that statistical comparisons of schools, based on test scores, showed no benefit for one configuration over another. But, he said, reconfiguring schools might still be useful.

"We think it provokes a conversation," he said. "By changing the grade configuration you bring everybody's attention to the fact that they need to be asking the right questions."

Since 1999, under New York State's tougher academic standards, fourth grade scores have risen sharply on the standardized English and math tests. But eighth grade scores have improved only modestly, reflecting what the state education commissioner, Richard P. Mills, has described as a lack of focus and mission at many middle schools.

In fact, the city's effort comes as the state Board of Regents is developing new curriculum requirements and other regulations for the middle grades, expected to be adopted in April, in response to five years of testing data that show widespread failure in middle schools all across New York State.

A preview of the city's initiative was offered Monday night on the Rockaway Peninsula in Queens, where the regional superintendent, Kathleen Cashin, won approval for a a plan to reconfigure five elementary schools and two middle schools, all but one of which would become grammar schools for pre-kindergarten to eighth grade classes next fall.

The remaining school, Middle School 180, will house a gifted program for grades six to eight. Dr. Cashin said that the K-8 model was in high demand among parents and that it offered numerous benefits, not necessarily tied to test scores.

"It's an elementary-like nurturing environment," she said. "Because children are older doesn't mean they don't need that nurturing care of a loving, caring adult. I have found the attendance is better, almost always. The violence is less, the younger kids defuse the older and the academics are at least as good if not better."

But Ernest Brown, a school board member who voted against the plan, said he was not convinced that more K-8 schools were the answer. "All of a sudden, K to 8. Does that mean the hormones won't be raging?" he asked. "All of a sudden, K to 8. Does that mean the children won't organize into cliques?"

As a result of the Rockaways plan, Dr. Cashin said, parents elsewhere in her region, including Howard Beach, Queens, were clamoring for similar changes to their middle schools. "Making it more like an elementary school is a plus," Dr. Cashin said. "If you look at private and parochial schools, they are almost always that structure."

But the city faces some difficulties in trying to reconfigure schools, including the physical limitations of existing buildings. Under its five-year, $13 billion school construction plan, the Education Department has proposed building up to 54 new K-through-8 schools and up to 23 6-through-12 schools.

Proponents of the 6-through-12 model say such schools offer a clearer path to college and that reducing the number of times that children switch schools alleviates social pressure. Critics, however, say that 11-year-old sixth graders are far too young to be in the same building with 18-year-old high school students.

The head of the teachers' union, Randi Weingarten, said changes to the curriculum and to student services, including a healthy balance of academic courses and enrichment classes such as art, were more important than the organizational design of the school.