Parents in Clinton Hill had nearly given up on P.S. 11. Once the gem of the district, the school had faded since the departure of a beloved principal 15 years ago. It hemorrhaged teachers, most of whom were unhappy with the subsequent administration, and test scores were in decline.

Meanwhile, the neighborhood was changing, as an influx of young families snapped up million-dollar homes on the up-and-coming blocks surrounding the school. A group of residents — some with their eyes on enrolling their children in P.S. 11 — got together to help the school. Within a few months, they had raised more than $30,000 to renovate the library, putting in new furniture and shelves.

When a new principal, Alonta Wrighton, was installed in September, she recognized the potential.

“The first thing she did was to reach out to the community … it made everyone feel included and empowered,” a former PTA president, Clement Rand, who is now the parent coordinator, said. “There’s been a major influx of parents bringing their kids back to the school — the atmosphere is really great.”

The formula for turning a failing school into a successful one has long eluded leaders in the New York City public school system. Since 2002, Mayor Bloomberg and Chancellor Joel Klein have tried to accomplish what none of their predecessors could: to replicate what is happening at P.S. 11, only at the citywide level. They have staked their careers on turning around a school system in which only half of the students can read at grade level, constantly tinkering in the search for what works.

A few city principals seem to have pinpointed one of the magic ingredients: parents. At schools in neighborhoods around the city where gentrification has diversified student populations, principals are harnessing the power of middle-class parents who have the time and resources to pitch in.

Ms. Wrighton removed the maze of filing cabinets and clutter from the main office in an effort to make it more welcoming. She recruited a parent to pick out colors for a new coat of paint in the halls. She enlisted another parent to help her write the school’s comprehensive education plan.

Now the parent group is on to its next project: working with the school to raise funds to renovate the auditorium and add a new greenhouse for the science program. Although this year’s test scores haven’t yet arrived to show whether student achievement is improving, Mr. Rand is confident it is.

“When the adults in the building are working together and working toward one common goal, it’s definitely beneficial to students,” he said. “You see that in the work they’re putting out and the behavior.”

At P.S. 84 on the Upper West Side and P.S. 8 in Brooklyn Heights, stories similar to P.S. 11’s have unfolded.

A group of neighborhood parents had been eyeing P.S. 84 for their pre-schoolers after a new principal was installed and the school’s test scores began to rise. One of the parents, Britt-Louise Gilder, who works part time at a stock brokerage, said she wasn’t certain it was a place she would want to send her daughter until she heard the principal say: “The road to improvement is getting more parents in here.” She immediately jumped into action, recruiting other parents to enroll their children and offering to raise funds.

A few years ago, P.S. 8 was slated for closure until a new administration drew in parents from the surrounding brownstones and from the nearby housing project to come on Saturdays and help clean up and paint the dusty, cluttered classrooms. Then, they sat them down to discuss fund raising and plans for restructuring the curriculum.

“We wanted to have some say,” a former PTA president at P.S. 8, Precious Jones-Walker, who now serves as the school’s parent coordinator, said. The school has since taken off, becoming one of the best in its district.

The director of school support in the Department of Education’s Office of Parent Engagement, Olivia Ellis, a former administrator at P.S. 8, is a firm believer in parental involvement as a catalyst for improving schools.

“It’s a matter of opening the doors and letting them come in and get involved,” Ms. Ellis said. “I know it can only work if parents are a part of it.”

She noted that something the three schools had in common was the arrival of more middle-class parents in the neighborhood. “A lot of it is through gentrification,” she said.

In some cases, this has led to strife, as different parent groups vie for control. At one school in Williamsburg, a contingent of middle-class parents proposed a yoga program that other parents at the school greeted with skepticism. At P.S. 84, Ms. Gilder said there is an effort to avoid a scenario where the school’s traditional base, which comes mostly from the surrounding housing projects, is left out. That means providing translated documents and inviting all of the school’s constituencies to meetings.

Achieving optimum balance often falls to the principal, however. Another major component to school reform is leadership, according to a journalist who has written about these schools for the Web site Insideschools.org, Clara Hemphill. “The parents can’t do it by themselves,” she said.

Messrs. Bloomberg and Klein have made leadership the centerpiece of their education strategy, with mayoral control the focus at the city level. At the school level, an intense effort to train new principals in the mayor’s Leadership Academy has been combined with the introduction of empowerment schools.

So far, many parent leaders say, their approach has left out an essential ingredient.

“When the history of this administration is written, historians will note that the stakeholders of the school system — parents and teachers — were left out of the critical policy decision making,” the president of the Chancellor’s Parent Advisory Council, Timothy Johnson, said at a November teacher’s union conference. “Parents are locked out.”

Ms. Ellis argues that parents have been prioritized with the creation of the parent engagement office and the $43 million investment in parent coordinators for every school in 2003.

Critics say these steps to include parents at the school level haven’t offset the closure of avenues for parent involvement at higher levels — where the biggest changes are taking place.

JoAnne Scichilone is a parent in Middle Village who was a District 24 Community Education Council member, a position appointed by the borough president, until she quit two years ago.

“I felt like I was spinning my wheels and wasting my time,” she said. “Nothing gets done. All the resolutions we pass mean nothing.”

In the long run, Mr. Johnson argues, it behooves the administration to pay attention to parents’ demands to be included. Widespread discontent among parents of the city’s 1.1 million public school students could hurt chances for the reauthorization of mayoral control when it comes up for a vote in 2009.

A Department of Education spokesman, David Cantor, pointed to new efforts such as the accountability initiative, which “is designed to provide parents with an unprecedented amount of information about the performance of their children and schools,” as evidence of the administration’s efforts to “enhance our partnership with parent leaders throughout the city.”

“We consider parent involvement in our schools at every level to be vitally important,” he said.

At P.S. 84, Ms. Gilder said she and the other parents who have pitched in to help improve the school aren’t asking to take it over.

“I don’t want to go to a school where I’m telling the principal how to do her job,” she said.

All she is asking, she said, is that the principal allow parents to be involved in the change.

“I’ve said to her, tell us how you envision using us, because we want to help you,” she said. “I need her to say, ‘Oh, I see the value of this.'”