When Galen Mook, 8, didn't arrive home at the expected time, Sarah Larson, his mother, began making calls around their Reston neighborhood.

Yes, Galen had stopped by on his bike, but he had left some time ago, both his grandmothers told her. But no, he hadn't been seen around Lake Anne Village Center, said Sue Schram, owner of the local used bookstore and Galen's great-aunt.

A neighbor, who happened to be in the bookstore and overheard Schram discussing Galen's whereabouts, provided reassuring news. She had just seen the boy with another neighbor's son tossing stones into a nearby pond.

Even though that was more than a decade ago, for Larson it still typifies what she has grown to value most about her neighborhood, Coleson Cluster.

"Everyone knows each other and everyone knows each other's kids," said Larson, whose parents moved to Reston from the Midwest in 1967, when she was in her teens. Like many of Reston's earliest residents, they embraced founder Robert E. Simon Jr.'s vision of a community where people would live, work and play.

Coleson Cluster, 47 two-, three- and four-bedroom flat-roofed, brick rowhouses, is a 10-minute walk from Reston's original "town center" on Lake Anne and the newer Reston Town Center. Set off from main thoroughfares and nestled amid towering oaks, the cluster embodies much of the small-town vision Simon had in mind when he drew up the town's master plan more than 40 years ago.

Larson, who shared that vision, bought her own three-bedroom townhouse in 1978, after graduate school, for $63,000. Fifteen years later, she and another longtime neighbor from Coleson founded the Reston Museum, dedicated to community life in Reston.

"There's a sense of community in Coleson you don't find in many places," she said.

The third of Reston's architecturally distinct neighborhoods to be built, Coleson was designed jointly by Simon and nationally recognized modernist architect Chloethiel Woodard Smith in the mid-1960s.

Simon and Woodard Smith incorporated features intended to promote interaction. To encourage people to socialize in public, for example, they de-emphasized back yards. Instead, most homes have a large front patio that bumps up against a public walkway.

In addition, Woodard Smith, who once said she liked her windows to start at the floor "because I love the feeling of looking down and out over the world," put floor-to-ceiling windows on each level of every house. Each house also has at least one set of sliding glass doors, many of which open onto the street level, allowing residents to watch neighbors pass by.

And unlike other nearby neighborhoods, Coleson homes don't have private garages. Instead, each grouping of six to 10 houses has a shared carport.

"The footprint of the buildings make it so that you run into your neighbors all of the time," Larson said. "You can't live here and be invisible. The people who live here bought into that philosophy."

Many of the cluster's longtime residents say things such as affordability and location originally drew them to Coleson. (New, Coleson homes, which range from about 1,500 to 3,500 square feet, sold for $30,000 to $40,000.)

Over time, they say, the neighborhood developed a spirit that is the main reason they stay.

For Sam and Eileen Harahan, who moved to Coleson in 1975 and raised four children in a four-bedroom townhouse, the cluster's location near a network of foot and bike paths linking to other parts of Reston was the initial draw.

A Brooklyn native who doesn't drive, Eileen Harahan said the paths provided her and her children with a lifeline.

"I wanted to live in a place where children could walk to school or to the swimming pool or to ponds to collect tadpoles," said Eileen Harahan. "I wanted to be able to walk and meet other people."

Carolyn Miller, whose family moved to Coleson in the 1970s after living on military bases abroad, said she found adjusting to the neighborhood easy, even as a rebellious teenager.

"We had lived all over Europe, and Coleson was the first place I ever felt at home," she said. "Everyone was so friendly."

One young man from the neighborhood, Jonathan Miller, was so friendly she eventually married him. After living elsewhere in Reston, the couple bought their own Coleson house in 1997.

"We knew we wanted to live in a mature house with lots of trees, and I had a lot of fond memories of the neighborhood," said Jonathan.

Susan Kane, who returned to the neighborhood in 2000 with her husband, Pat, and youngest daughter, Amanda, said moving back to Coleson was "like putting on a comfortable old slipper."

As newlyweds in the late 1960s and early 1970s, the Kanes bought two houses in Coleson. They lived in the neighborhood for a few years before moving into a much larger, stand-alone house on Lake Anne, where they raised six children over 27 years.

However, neither they nor their kids lost touch with the friends they had made in Coleson, Susan Kane said. "It was so comfortable coming back here. On the lake, we only connected with two or three families."

Kane said she's particularly gratified that neighbors have taken the time to get to know Amanda, 23, who has Down syndrome. When Amanda walks her dog, most people stop to make conversation and, these days, ask how she likes her new job.

When Amanda was a teenager and wanted to join the swim team at North Shore Pool, the closest of several public pools open to Coleson residents, she was welcomed.

"The coach said, 'Why shouldn't she be able to participate?' " her mother recalled.

But not everything about Coleson has worked out as planned. The flat roofs have been a constant source of annoyance because they frequently don't drain properly and tend to leak, particularly after snow and ice storms.

"We just try to overlook the problems with the roofs," said Sam Harahan who, like most Coleson residents, occasionally must climb up on his roof to ensure that water isn't backing up.

Then there's the "experimental" groundwater drainage system that silted up early on and caused some of Coleson to flood. And the "environmentally friendly" air-conditioning system that was supposed to rely on chilled water from Lake Anne to keep the houses cool but has never worked just right. Coleson homeowners can individually adjust the heat in their homes during winter, but not the cool air during summer.

But those inconveniences are outweighed by the benefits, said Susann Gerstein, who moved into Coleson in 1979 with her husband, Bob, and raised three boys. Two years after settling in, she opened a children's consignment shop she still runs with another friend from Reston and, in 1994, opened the Reston Museum with Larson.

"There's a wonderful sense of continuity within Coleson and in the larger Reston community, in general," she said. "People who used to come into the store with their mothers now come in with their own children."

"Coleson has a quiet charm," she said. "It's not flashy, but it's a great place to live."

Coleson Cluster's 47 flat-roofed brick rowhouses cost $30,000 to $40,000 in the mid-1960sAmanda Kane grew up in the neighborhood in the 1970s and has now returned.Barbara Fraize has been living in Coleson Cluster with her husband, Bill, since July 1969. Carolyn and Jonathan Miller lived in Coleson Cluster while they were growing up. Carolyn, whose military family moved a lot, says Coleson was the first place she ever felt at home.