The roomy, clapboard house, with a wrap-around porch and shingled roof, has all the charm of Tom Sawyer's birthplace. But instead of looking out onto the rolling Mississippi, this newly built house sits at the heart of Reston's final frontier, a huge quadrant of land known as North Reston and just recently opened for development.

Most of the first houses at North Reston's North Point Village have a distinct Victorian flair, in stark contrast with Reston's predominantly contemporary architecture. And while there are other less-traditional homes in the works, the down-home feel of the first few are an indication of the direction Reston's developers have chosen for the town's newest neighborhood.

Conceived more than 20 years ago, Reston pioneered the concept of the planned community. But despite the careful strategy, not all has gone according to design. The majority of Reston's village centers have been less than successful at attracting retail business, the pathways have been plagued with crime and Reston's scenic amenities--the lakes and open spaces--are proving expensive to maintain.

So in North Reston, which covers 1,500 acres of wooded land bounded by Rte. 606 on the south and Rte. 7 to the north, the current developer--Reston Land Corp., a subsidiary of Mobil Oil Corp.--is scaling down. Plans are to create a community that will look more like the original, more densely-built development at Lake Anne than the 1970-vintage South Lakes homes, which are generally larger.

"North Reston is going to be a much more intimate development than what went in south of the Dulles Access Road," said commercial realtor Karl Ingebritsen of Wellborn Management Inc. in Reston. "In Hunters Woods and South Lakes, there are large-scale developments, like Shadow Wood, with hundreds of units of housing. But when you look at the map for North Reston, you can see that Reston Land Corp. is planning smaller clusters of homes, and fewer houses of each type. It's going to have a different feel."

Reston Land officials say their plans for North Point Village merely reflect the demands of the local housing market.

"Reston always has been finely tuned to the marketplace," said Reston Land Vice President for Marketing Michael Was. "It had to make it through the 20 years of changes we've had in the market."

But Was admits that those changes have made it difficult to keep Reston on track. Although the original design concept was to nestle houses and employment centers together in the same community, business development along the Dulles Access Road lagged behind expectations, and, during the '70s, Reston slipped towards becoming a bedroom community.

Despite efforts to mix low- and middle-income housing, Reston's builders took advantage of the spectacular housing market of the mid-'70s to concentrate on building expensive, lake-front town houses for investors interested in cashing in on the housing boom. When interest rates rose in 1980, Reston builders were left with many unsold units, most of them in the $120,000-to-$150,000 price range and out of reach of the homebuyers of the '80s.

Reston Land is trying to avoid a similar problem as it completes the development of the South Lakes area and starts in at North Point Village. For example, it has started working more closely with builders so that it can control the types of houses built. In the past year, it has concentrated on offering a variety of homes, and currently has more than 100 models for sale, ranging in price from $60,000 to $750,000. The effort has paid off: Reston netted 537 new-home and condominium sales in 1982, up 91 percent over 1981.

"North Point Village has sold beyond our wildest expectations," said Was, adding that he believes this is the start of a long-term boom in Reston sales. The total number of jobs in Reston rose above the number of housing units last year, and the scheduled opening of the Dulles Toll Road in 1984 adds to Was's optimism about North Reston.

The push for variety at North Point Village has resulted in what Ingebritsen sees as a development similar to Lake Anne in its intimacy, but in radical contrast with the original development.

Perhaps most telling is that the future North Point Village center probably will look more like a standard suburban shopping mall, with storefronts facing a parking lot, than any of its predecessors in Reston. The South Lakes Village Center--now being built between Reston's two South Lakes--faces a parking lot, with only a small plaza down on the lakefront.

"It's a compromise between a commercial strip development and the other village centers, which have been pedestrian-oriented," said Was, indicating that North Point Village's center, which is tentatively planned for construction about eight years from now, probably will be similar to the suburban-style South Lakes center.

North Point Village center will not be on a lake, partly because Reston Land has decided to scale back the number and size of the lakes in North Reston. Instead of three lakes, Was said Reston Land may stop with the tiny Lake Newport, which has already been built, primarily for storm drainage. Plans for a second lake to the west already have been abandoned, and the proposal for a third lake to the north remains on the drawing boards. Pathways also have been redesigned, running much closer to roadways rather than through the woods.

But North Reston's most marked deviation from the original Reston scheme may be that there is little chance of any subsidized housing being built there. When rezoning was approved for North Point Village, Reston Land refused to promise that it would include subsidized housing in the development, but instead agreed to hold a parcel for four years that could accommodate 200 garden apartments, 15 percent of which would be subsidized. If Reston Land cannot find a builder by 1986, it will sell the parcel for other housing.

Although plans for the first apartment building to go up in Reston in eight years were approved recently, the site is in Lake Anne rather than North Reston, and it may be years before the success of the venture can be determined.

Fairfax County Supervisor Martha V. Pennino (D-Reston) said at the time of the rezoning approval for North Reston that her constituents support low-income housing, but that they don't want all of it put in Reston. Recent cuts in the federal housing subsidy programs also decrease the likelihood that North Reston will be the site of a housing project.

By melding what has worked in Reston with changes to correct mistakes, Reston Land may have a community at North Point Village that represents a compromise between social experiment and a more standard suburban community. But it appears now that the compromise sells.