A selective secondary school due to open next year in Harlem affiliated with Columbia University faces high expectations that extend beyond academics.

The Columbia Secondary School for Math, Science, and Engineering, planned as a public magnet school covering sixth to 12th grade, is part of Mayor Bloomberg’s re-election campaign promise to add seven selective schools by 2009, a proposal apparently designed to appeal to middle-class voters. The school may also be perceived as an olive branch to minority and low-income families: Its ultimate location is inside Columbia’s planned expansion into Manhattanville, which some community members have opposed in fear it will displace them.

That the school will be an academic success seems nearly certain. A Nobel Prize winner has consulted school planners, and its future principal is a dynamic educator with decades of experience. Many of the teachers the school plans to hire will have Ph.D.s from Columbia, and eventually its older students will have the opportunity to take college-level classes at the university.

It is unclear, though, whether it can succeed at deterring local middle-class parents from sending their children to private school or moving to the suburbs while serving a needy local community with a dearth of quality schools.

The strikingly diverse crowd of parents and children — hundreds more than administrators expected — that converged onto Columbia’s campus for the school’s first open house on Saturday represented the divergent expectations for the school as it prepares to open its doors next year.

Raul Chirriboga, 10, was standing in line with his mother, a recently arrived Ecuadorian immigrant who carried a bilingual flyer about the school that was handed out at his elementary school in Washington Heights. He said he was interested in Columbia Secondary, which will launch with just a sixth grade next year and add a grade every year, because his classes now are too easy.

“I want to challenge myself and be smart,” he said.

For Shanelle Mills, 11, a student at an elementary school on the northern edge of Harlem, her interest in the school was even more basic.

“Our school is old and they are always starting fights,” she said. “I want to go to a school where they really teach the children.”

Peri Muldofsky, who lives on the Upper West Side and sends her 10-year-old son to a gifted and talented program, said she was curious about the school because of the difficulty of getting into the city’s other selective middle schools, many which are outside of her district.

“There’s not as many alternatives as people say there are,” Ms. Muldofsky said. “I think that’s why you’re seeing the gigantic turnout.”

While the diversity poses a challenge, many standing in line for the open house also saw it as a source of hope.

Hal Harris, a member of the NAACP who fought to get slots for community children when Columbia constructed a private elementary school for the children of faculty and staff, waited outside for over an hour at the open house to find out about the school as a possibility for his fifth-grade daughter.

Referring to Manhattanville residents, he said the opening of the school is probably a “public relations giveback because they’re railroading the community.” But he added: “It’s great that they’re giving an opportunity for our community.”

The school will be located inside a nearby public school until the new building is constructed, and Columbia officials say a place for the school will be found regardless of whether the Manhattanville campus expansion is approved by the city.

Because it will start with the sixth grade, the school won’t administer the exam used by other selective high schools, such as Stuyvesant and Bronx High School of Science. Instead, an admissions process has been developed especially for the school that is intended to be blind to gender, race, and class.

That doesn’t mean the school’s planners aren’t making a concerted effort to ensure that the school is representative of its community. At the beginning of his presentation Saturday, the school’s project director and future principal, Jose Maldonado, who holds a doctorate from Columbia’s Teachers College in science education and has spent many years working in private schools in Puerto Rico, joked that the overwhelming turnout perhaps was a sign the open house was too open. In fact, Mr. Maldonado was a part of the reason for the size and diversity of the crowd. For the past several weeks, he has traveled across Harlem, Washington Heights, and the Upper West Side to meet with parents and pass out flyers. During his presentation, he alternated between Spanish and English. When he talked about opportunities for studying abroad, he also emphasized that the school was committed to equity and making sure all children could do so.

The open house, the first in a series, lasted an hour longer than scheduled, as more than 600 parents and children eagerly peppered Mr. Maldonado with questions. The widespread enthusiasm is perhaps a sign that the math, science, and engineering school will satisfy all the sectors of the community. At the same time, making everyone happy is a math problem that even the science and math doctoral students designing the school may not be able to solve.

The school has only about 100 slots per grade, with preference given to students living above 96th Street in Manhattan.

“All parents want the best opportunities for our children,” Mr. Harris said. “They’ve got a task on their hands.”