Karen Helbrecht and Gordon Johnson had not investigated the local elementary school before they bought their light green Cape Cod house in the Del Ray section of Alexandria. But after they became parents, they had some concerns about how the school would fit the needs of their daughter Maggie.

She was a quiet 4-year-old with short, light brown hair and a love of ballet. Exposed to a noisy playground, she often did not assert herself. Whichever way she was pushed, she went. Her mother remembered her own shy and withdrawn girlhood, which did not change until she reached college and found herself playing dance-fever cello for an Irish/English folk band.

If Maggie was to go to public school, it would be the Mount Vernon Community School, six blocks away. It was in an old brick building, parts of it dating back to 1925, bursting with the children of immigrants. The playground was the kind of crowded, high-decibel place that seemed to intimidate Maggie. And the school had the lowest test scores and the highest percentage of non-English-speaking and low-income families in the city.

A couple next door, after pondering whether they wanted their child in that school, moved to North Arlington instead. Another couple two doors away had decamped to McLean. Both families said they needed bigger houses, but Helbrecht and Johnston sensed they were also concerned that Mount Vernon might not be the best place for their kids.

Like millions of other parents, Helbrecht and Johnston believe that providing a challenging and enriching education for their children is one of their most important responsibilities. But what was a good school, and how could they tell if Mount Vernon was one?

I have thought a lot about those questions. In the last few years, as I've written stories about education for The Washington Post and published two books about high schools, strangers have begun calling and asking for advice. They say they want to know where the good schools are. Many say they enjoy life in Silver Spring, or Dupont Circle, or South Arlington, or Temple Hills, or Capitol Hill, or Hybla Valley, or any of dozens of local neighborhoods whose ethnic diversity and immigrant vibrancy they find irresistible – until they begin to wonder if the local schools are right for their college-bound kindergartner.

At first I didn't think middle-class parents needed help from me. I was more interested in the low-income and minority students in the schools they were thinking of abandoning.

Then I remembered that I, for all my high-mindedness, had experienced the same parental fears. Nineteen years ago my wife and I pulled our oldest child out of an overstressed public school in California just like the ones in their neighborhoods. The question they were asking – how to choose a school – was an important one. And the story of Mount Vernon Community School and the neighborhood surrounding it provides a good example of the uncertainties many families face.

Both Karen Helbrecht and Gordon Johnston grew up in California and attended public schools there. Helbrecht is dark-haired and willowy. Johnston has light brown hair with a touch of gray and very blue eyes. They came to know each other in California as members of a folk band, Fyne Companions.

In 1987 Johnston, a space program manager, accepted a temporary assignment at the Washington headquarters of the National Aeronautics and Space Administration. They were about to marry, and they decided to buy a home, something inexpensive and near a Metro stop. They paid $118,000 for what was then a severely dilapidated wood frame house on Windsor Avenue. Helbrecht, arriving after her fiance had made the deal, was not impressed. "It smelled funny," she recalled. Police sirens were common in the neighborhood. A stroll in the weedy vacant lot next door often yielded empty beer bottles and fresh garbage.

But they settled in. Helbrecht, with two degrees in geography, found work at the Federal Emergency Management Agency. And they learned to love Del Ray. It is wondrously diverse, with most of the families on Windsor Avenue living next to someone of contrasting ethnicity. The houses are a funky mix of old brick, restored Cape Cod and fake Victorian. Some owners stay only a short time, but many others add rooms and landscaping and call it home. Gordon rides his bicycle across the 14th Street Bridge to work each day. Karen takes Maggie and Janet, their younger daughter, to the library every Friday for a helping of family favorites like The Three Little Wolves and the Big Bad Pig.

But as Maggie reached her fifth birthday, the old school at 2601 Commonwealth Ave. became something they had to think about. It was in many ways not an attractive prospect.

The building that housed much of the school began life 75 years ago as George Mason High School. The original Mount Vernon Elementary School, situated elsewhere in the city, no longer exists, but its 1907 school bell sits in the Mount Vernon media center to be rung on special occasions.

Many neighbors told Helbrecht and Johnston the school had passed its peak. By the time Maggie was ready for school, Mount Vernon had 720 students, the largest elementary school in the city and 120 more than what the school board hoped would be the maximum.

Half the school population was Hispanic, and a quarter lived in homes where Spanish was the preferred language. Forty percent were African American. Nearly 80 percent came from families whose incomes were low enough to qualify for federally subsidized lunches – an economically disadvantaged group known to be at-risk when it comes to traditional measures of educational achievement. Nearly half the faculty were newcomers with three years or less experience.

In 1998 the state of Virginia had begun giving a series of tests in reading, mathematics, science and social science to children in grades 3, 5 and 8 and high school. The state school board said any school with fewer than 70 percent of its students passing these Standards of Learning (SOL) tests by 2007 would lose its accreditation. Last year's results for Mount Vernon showed only 48.6 percent of third-graders and 50.3 percent of fifth-graders passing the reading test. Forty-eight percent of third-graders and 27 percent of fifth-graders passed the mathematics. The history results were even worse: 21 percent of third-graders and 13.7 percent of fifth-graders passed. The scores were well below the state averages.

Some Alexandria administrators acknowledged privately that without significant changes in the way the tests were scored, or a relaxation in the state's requirements, chances were that Mount Vernon would lose its accreditation. The new principal, Lilia "Lulu" Lopez, put it more gently: "It's going to be very challenging unless we get all the resources that we need."

Nineteen years ago, my wife and I enrolled our son Joe in the second grade at Allendale Elementary School in Pasadena, Calif. The city was similar to Alexandria. There were many low-rent apartments and small houses as well as pockets of wealth. Many of the students at the school came from low-income families.

Joe, like Maggie, was a curious child who loved books and music, and seemed to do fine in school. But there were more than 30 students in his class. The homework did not seem very challenging. Parental participation was low. And then we noticed a homework assignment in which his young teacher had misspelled two words. We found Joe a place in the Chandler School on a rise overlooking the Rose Bowl. He never again attended a public school.

Now I wonder if we made a mistake. In the intervening two decades I have seen many children thrive in schools like Allendale and Mount Vernon. It is clear to me that, given competent teachers – still prevalent even in the poorest American schools – children like Joe and Maggie can succeed in classrooms with many low-income and low-achieving students.

The research on this question is broad and deep, based on repeated efforts to assess the impact of school desegregation in the 1960s and 1970s. The headlines focused on another conclusion of those studies: that the academic performance of African American students did not improve very much when they were put in classrooms with whites. This statistical fact doomed efforts to accelerate integration and killed many busing plans.

But those same studies also showed that higher-scoring white students did not suffer academically for being in classes with lower-scoring minorities. Some whites did poorly, and some blacks did brilliantly, but on average their performance was what it was before they were mixed. "If you look back at the meta-analysis of school desegregation studies, time and again white and middle-class students are not harmed by integration. Their test scores did not go down," said Amy Stuart Wells, professor of educational policy at the University of California at Los Angeles.

Much of the scholarly work on school segregation in recent years has been done by Gary Orfield, professor of education and social policy at Harvard University. When he was working at the Brookings Institution in the early 1970s, he and his wife enrolled their daughters in Peabody Elementary School on Capitol Hill. Other college-educated couples joined them. "We learned there are lots of successful teachers even in schools that have terrible reputations," he said. Many years later, one of their daughters is a ballerina, one a lawyer and one a teacher.

At Maggie Johnston's house, books overflow the shelves in nearly every room. In the living room with its light wood floors, one bookcase has Winnie the Pooh, The World's Greatest Fairy Tales, The Runaway Bunny and Shel Silverstein's A Giraffe and a Half sitting right next to books by Michael Crichton and John Grisham. The shelf in the girls' room, where Maggie sleeps on the top bunk and Janet on the bottom, has 101 Dalmatians, The Wind in the Willows and Stuart Little, among others. Each night Karen or Gordon reads to them, usually at bedtime. There are library visits and trips to musical performances. Maggie has been lobbying for violin lessons; Janet wants to be a cellist like her mother.

When parents who have created homes like that call and ask where their children should go to school, I tell them that at least until adolescence, it doesn't really matter, unless their child has special needs. The school they select, as long as it is safe and secure, will be fine if they are reading and talking at home.

Mount Vernon, like the vast majority of American schools, devotes many resources to its low – performing students, but it also gives its fastest students plenty to do. Federal and state dollars for gifted education – called the Talented and Gifted (TAG) program in Alexandria – are helpful. Enough is being taught to keep the best students within range of their counterparts at schools in tonier neighborhoods.

Consider Mount Vernon's best students. Jamestown Elementary School in North Arlington is one of the highest-scoring elementary schools in the state. It is just the kind of school that lures worried parents away from neighborhoods like Del Ray. In 1999 its five highest SOL scores in fifth-grade reading were all a perfect 600. Yet Mount Vernon's top five fifth-grade reading scores were in the same league: 600, 559, 559, 522 and 522. That meant one test with no wrong answers, two with one wrong, and two with two wrong.

Elementary schools almost never publish the test results of their highest-achieving students. Educators prefer to measure themselves by how successful they are in coaxing every child to learn. But middle-class parents, skittish as Kentucky thoroughbreds, still need the reassurance. Publishing some of the best scores every year – no need to identify the students – might ease anxieties. Even just a few high scores illuminate a school's deeper efforts to teach everyone; they stand out like bright red letters on the top of a chocolate-frosted birthday cake.

Yet parents of extremely well-prepared children, like everyone else, need to get a good sense of a school before they enroll. Confidence in the school is vital, and few people can be happy with a choice unless it is a well-informed one. The checklist on page 19 suggests what to look for, but two points should be underlined.

First, knowing the principal is crucial. A distracted, incommunicative or exhausted principal can poison the atmosphere. Call up the Mount Vernon Web site, www.acps.k12.va.us/mtvernon/MVHomePage.html, and you discover that principal Lopez has 30 years' experience as a teacher and administrator in three different districts, including an assortment of high-level jobs in Los Angeles. Finding Lopez in charge of your elementary school is akin to having Sparky Anderson coach your Little League team. The Web site notes that the assistant principal, Carroll Williams, also has experience at elementary, secondary and college levels, and was until recently Alexandria Superintendent Herbert M. Berg's chief troubleshooter. Lopez's predecessor, Gayle Smith, won a Washington Post education leadership award.

Second, the local high school has an extraordinary influence on the entire school system. Don't ignore the middle school – it's good to know if the one in your area encourages students to take algebra by the eighth grade. But the key grades are 10, 11 and 12. At that point, even college-educated parents lose their ability to make up for what the school lacks.

In the early 1990s I worked in New York as the Post's Wall Street reporter. The job was very much like covering schools. Both stocks and children make progress some days, and languish other days. Market analysts had statistics to distinguish good years from bad. As in education, there were many explanations for why things happened and too many factors involved ever to be sure the explanations were correct.

Whenever the market encountered unusual difficulties, I would call experts around the country. One piece of advice stuck with me. The best analysts would always conclude by telling investors: Decide how much risk you can stand. If a particular stock, no matter how attractive, is going to ruin your appetite and leave you staring out the window, don't buy it.

The same applies to parents deciding where to send their child to school. No matter what the neighbors say, no matter what the test score trend, if you feel good about a school, you should send your child there. If you don't, keep looking.

Helbrecht and Johnston understood why other couples had abandoned Mount Vernon, but the more they heard of the school's problems, the more they wanted to help make it better.

Long before Maggie entered kindergarten, they became involved in a political debate over redrawing school boundaries. In public hearings, each would go to the microphone; their different last names gave them a chance to double their input. They opposed plans that would hurt Mount Vernon's efforts to reduce enrollment. They applauded the plan for a new language immersion program at the school.

On the first day of school this past September, mother and father appeared to be more excited than daughter. The entire family walked the six short blocks to Mount Vernon. Maggie had on a new outfit, including new shoes, and a backpack full of school supplies. She smiled for parental photographs, then happily waved goodbye as she walked through the glass doors and into her new life.

Maggie's kindergarten class, in Room 102 on the ground floor a few skips from Mount Vernon's front entrance, is full of light. It is a large space, 20 feet by 40 feet, with big windows at the west end. Building blocks and dolls and books and letter boards and soft brown couches and sinks and more books line the walls. In the middle of the room, 19 children sit on small blue plastic chairs at four long tables.

Their names are Maleke, Alex, Maicol, Amilcar, Marvin, Luis, Jose, Erin, Sara, Rony, Andrea, Corneil, Betty, Amy, RaQuell, Carlos, Monique, Yesly and Maggie. Only three or four, including Maggie, have parents with college degrees, but all the pupils seem eager to learn. The teacher, Debby Duffett, is a seasoned professional. For many years she traveled the world as a Foreign Service officer's spouse. She taught in Nicosia and Port-au-Prince and developed a feel for reaching children across cultural barriers.

Duffett and the classroom aide, Marta Garrido, have been working together for more than eight years. David Letterman and Paul Shaffer would admire their technique. During one recent afternoon session, their young audience was attentive and obedient, responding quickly to a joke, a soft word or an occasional ping from Duffett's melodious triangle.

"Mrs. Garrido," Duffett said during a restless moment, "I want you to notice how quiet Rony is while we are reading the story." When a boy became too rambunctious during snack time, Duffett said, "Alex, did you see what a nice job Betty is doing at the table?"

Maggie Johnston wore a white and red turtleneck, bright red tights and black buckled shoes. When her best friend and tablemate, Sara, daughter of Ethiopian immigrants, was engaged elsewhere in the room, Maggie briefly tolerated a discussion with RaQuell over whether they were boyfriend and girlfriend, but her prime focus was on her work. She polished off an arithmetic exercise-matching pictures of coin collections with their values – in less than a minute. During reading she sat on the floor in front and quietly absorbed every word of The Napping House.

Duffett told me Maggie is already reading. She picks up new words at first sight and is progressing well, the teacher said.

As for her lack of assertiveness, that no longer seems to be a problem. "When she feels pushed around, she speaks up," her mother said. "That was sort of a concern at the beginning of school, but not too much now."

At St. Elmo's Coffee Pub on Mount Vernon Avenue, Karen Helbrecht and other mothers with children at the Beverly Hills Church preschool gathered one recent morning for coffee, bagels and a chat amid old couches, house plants and sun streaming in. Children sat on high stools at a window counter and watched the world stroll by.

The mothers – there were no fathers this day – discussed their concerns about Mount Vernon Community School, and what might happen to their children in a building so full of new teachers and untutored classmates. But they also exchanged hopeful news.

"I have a neighbor down the street who sent three of her children to Mount Vernon," Diane Hill said. "Her oldest is in college and he is at U-Va."

The student in question was Ben Webne, a tall and athletic 18-year-old freshman at the University of Virginia, the state's most prestigious public university.

"He went to U-Va.?" another mother said, very impressed.

"Yes, he did," Hill said.

Such conversations have an emotional impact on the participants. If a family sees that an elementary school provides access to a high school that has a good record in preparing students for schools like U-Va., then they are often willing to bite their tongues when parents night is poorly attended or their child complains that the bathrooms stink.

Their children go on to Alexandria's sole public high school, T.C. Williams, and to good colleges. They give the high school credit for this, even though much of the responsibility for that success is theirs.

To Ben Webne, pursuing an architecture degree and playing a little club baseball on the side, his status as a poster child for the Mount Vernon Community School is amusing and a bit ironic. There were days, he said, when he hated the school. He was one of the smart kids in the TAG program, a cause for taunts on the playground.

Still, he said, he is glad he attended

Mount Vernon. Whenever he meets someone from a different culture at multihued

U-Va., he notices that he is more comfortable than the white prep school graduates who still make up a substantial part of the university's student body. "I feel like I am a step above those kids," he said.

And yet, should Mount Vernon, or any school, take the credit or blame for what he has become? Webne does not think so. "I just had parents who pushed me," he said..

Jay Mathews covers education for the Washington Post Metro section.