Mary Harlow moved to Blueberry Hill in Vienna in search of a supportive community. The day she needed help, that support was just 20 feet away.

Harlow's knee gave out while she was walking across her lawn. She was able to make it to the porch of a neighbor, who drove her to the hospital. She learned she had torn the cartilage in her knee and would be incapacitated for weeks. As soon as she returned home, neighbors at Blueberry Hill, the first "co-housing" community in Northern Virginia, delivered cooked meals, took out her trash and stopped by to visit.

The co-housing concept was developed in Denmark in the late 1960s. Communities using it are made up of single-family houses that share extensive common facilities. Usually, co-housing communities consist of 20 to 30 houses designed by the residents and connected by a pedestrian walkway or courtyard.

"I can't tell you how glad I am to be in co-housing," Harlow said recently, on the day of a party to celebrate the opening of Blueberry Hill's common house, a building with a big community kitchen and dining room, as well as a porch and lounge where neighbors can gather.

Blueberry Hill's 19 houses were built in groups of five each, starting in March 2000. As is characteristic of co-housing communities, the houses are designed to increase residents' opportunity to interact with neighbors, said the project's architect and now-resident, Jack Wilbern of McLean-based Butz-Wilbern Partnership. The homes face a central pedestrian walkway, with kitchens at the front of the house, opening off wide front porches. There are no roads within the community.

The style of the homes is "Virginia farmhouse," Wilbern said. That is in keeping with their location on a portion of Potomac Vegetable Farms, an organic farm that still operates around the houses. Steep roofs, simple forms, a variety of roof lines and wide front porches are reminiscent of Virginia's tidewater farmhouses.

Compared with many homes in other co-housing communities, Blueberry Hill houses are relatively large, though much smaller than many new houses in the Washington suburbs. There are two floor plans -- 2,200 and 2,550 square feet, rising two or three stories, respectively.

Because the owners wanted a community that was different in many ways from the usual tract-house neighborhood, the builder, Bozzuto Homes of Greenbelt, said the project took longer than normal for a development this size. "This was our first co-housing project," said Chuck Covell, vice president of Bozzuto Homes. "We took it on as more of an experiment than a money-making venture."

The cost of each house came to about $300,000, Wilbern said. Building materials and construction accounted for about a third of that. The rest included land -- 6.5 acres carved from the farm, plus an access road -- taxes, rezoning fees and property improvement, he said.

Residents, who designed the community as a group, chose to pay extra for such environmentally friendly features as geothermal heating and cooling systems (ground-source heat pumps), a greenway (pedestrian path) through the middle of the property, and tightly clustered houses set far from the main road with trees preserved around the periphery. At least $30,000 per house went to pay for these features, Wilbern said.

At times, the builder "thought we were kind of nuts" for stepping outside of proven housing development design, Wilbern said.

The homeowners "had tremendous expectations of things they wanted to accomplish with very little budget to accomplish those things," Covell said.

"Green building is a wonderful thing," he said, but often costs significantly more than conventional construction. For example, the geothermal heating and air conditioning that residents decided on cost $9,000 more per unit than traditional systems.

Bozzuto worked with the residents for two years prior to construction to make budget compromises, Covell said.

The work of the Blueberry Hill residents and Covell's team paid off when Bozzuto Homes, a division of the Bozzuto Group, won the Maryland-National Capital Building Industry Association's annual Environmental Builder of the Year award.

But these "green" building techniques that demonstrated sensitivity to the environment made the project too expensive for at least two families involved in the early planning. As costs rose, they dropped out. "It was gut-wrenching . . . like losing members of your family," Wilbern said.

In December 2000, the first five houses were completed and residents moved in.

Jackie and Ted Kramer were in that group. They live at the top of the hill, next door to Wilbern and his family. After less than two years in Blueberry Hill, the Kramers will be the second of the community's 19 families to sell, if all goes according to plan this fall. They are moving to another state to be closer to family. Their time in the community "has been great," they both agree.

Like many of their neighbors, the Kramers moved to Blueberry Hill from elsewhere in the Washington region. The Kramers had lived in Arlington, and Harlow had moved from a housing development about a half-mile away.

The shortest move, by a resident who says she is not planning to relocate again soon, was that of Anna Newcomb Bradford, daughter of Potomac Vegetable Farms' owner, Mariette Hiu Newcomb, who owned the land on which Blueberry Hills was built. She and her sister, Hana Newcomb, grew up in their family's farmhouse on another part of the property.

In the community spirit characteristic of the neighborhood, one of Bradford's friends and neighbors, Bernice Peltier, recalls joining in a line to pass boxes from the old farmhouse to Bradford's new house.

Other residents came from farther away -- Janet Greene and her family hold the record so far with their move from Oakland, Calif. They would have considered an intentional or co-housing community there, but most were in urban areas. "I wouldn't let my kids off the front porch," she said.

Nearly all of the residents of Blueberry Hill are new to the concept of co-housing. The ways they heard about the idea and the community vary widely. Ilene Landon, who at 30 is one of the younger homeowners, saw a flyer in a coffee shop in North Arlington where she and her husband often spent time. Greene found the community online while looking for an intentional community.

Resident Karen Vamberi was looking for a rental property and saw an advertisement for Blueberry Hill in the newspaper. She "thought it would be a good place to raise a family," especially since her husband travels for work. Her neighbors, Cathi St. Sure and her husband, John Caye, found out about the community through Caye's colleagues when the couple transferred to the area.

Caye, an Air Force architect, studied co-housing in graduate school and dreamed of developing his own co-housing project one day. For now, Blueberry Hill makes a safe place to raise their curious and daring 3-year-old daughter, who has a "tendency to wander."

Peltier and her husband had been Potomac Vegetable Farms customers for 15 years and knew the Newcombs because their children went to the same school. They had become enthralled with the idea of co-housing after reading an article about it in 1994. When Anna Newcomb Bradford suggested they consider the Blueberry Hill project, "we wanted to hug her," Peltier said.

Landon and her husband were the last family to move to the community, about a year ago. Even though they missed the years of planning and construction and community design, they said they think that they have fit in quickly and that the community has been friendly. At the recent community center grand opening, Landon sat next to the two other newest residents, Vamberi and St. Sure.

Landon admits to feeling ambivalent before moving in. "I'd never heard of co-housing before. . . . I was overwhelmed by the concept," she confessed. But now, she said, she's convinced, "it was the best decision we could have made."

Landon cautions against thinking co-housing is too community-focused.

"You can choose not to be social. . . . There are a couple of families we rarely see," she said.

Though she and her husband usually spend anywhere from one to six hours a week interacting with neighbors, they still have many friends who are not at all associated with Blueberry Hill.

Landon and her husband and Vamberi recently cooked dinner for 35 of their neighbors. The groceries for the menu, which included pad thai and curry, were covered by the $4 that each resident kicked in. Neighbors cook as many as two dinners a week at the common house. There are usually around 30 people at each dinner, Landon said.

"There is the expectation that everyone does something to help out the community" on a regular basis, explained Landon.

Rebecca Groisser and her best friend, Denise Funsten, needed no encouragement. The two 10-year-olds started a community newsletter this summer that they distribute to other children and to adults.

Though residents talk about how family-friendly Blueberry Hill is, the community is not limited to nuclear families with young children; empty-nesters, childless couples, divorcees and widows are all represented.

Resident Cookie Mandell said the sense of community at Blueberry Hill is greater even than in the small town where she grew up. "People are more committed . . . more responsible here," she said.

There is a strong motivation to mend fences, Mandell said. "We have to work together, so there's a big incentive to clear the air."

And, she said, people go out of their way to keep an eye on each other's children.

Mandell and her husband have a blended family of five children. Some of the neighbors in their previous neighborhood only interacted with the children when they had bounced their balls too hard or made too much noise, said Mandell. And when they left their former home in Reston to move to Blueberry Hill, Mandell said, she "wouldn't have recognized half of the families" in her neighborhood.

Her children like Blueberry Hill, Mandell said. When the family first moved in, she had to remind her daughters that they did not have to ask permission to play outside. Now she only asks them to tell her when they are going over to the farm (a quick walk through the woods) or inside a friend's house.

Because co-housing is still relatively rare in the United States, Harlow said, her friends fall into two camps regarding her new neighborhood: "those who think it's really neat and those who think it's really crazy."

Her family is nearly unanimous in thinking it is a good idea, she said -- her grown daughter even returned home to live for awhile and enjoyed it.

Rebecca Groisser, left, and her best friend, Denise Funsten, pick blueberries at the community. The 10-year-olds also started a community newsletter this summer.