Arlington County is waging a drive to bring back families.

Once predominantly a family community, the county in recent years has felt the same demographic forces that have hit older, close-in suburbs all across the country. Many of its families have moved farther out seeking larger houses and more space, while the children of others have grown up and gone -- to suburbs with cheaper housing or to other parts of the country, leaving an aging, increasingly single population behind.

Those trends, coupled with a limited supply of land on which to build new single-family homes, have touched off something of an apartment boom in the county recently. Developers have built more new apartments in Arlington in the last year than during the past 10 years, according to Mary Margaret Whipple, vice chairman of the Arlington County Board.

But Arlington real estate agents say the county's existing single-family home base -- with a wide range of styles and prices from below $100,000 to $1 million or more -- can be strong competition for houses in developments in the distant suburbs of both Maryland and Virginia.

Armed with a new, colorful information package prepared by a volunteer Citizens Task Force for Families, Arlington is selling itself to relocation services, real estate agents and the major corporations that call Arlington home. A whimsical new map shows schools, parks, recreational centers and tourist attractions. It emphasizes that four bridges from Northern Virginia to the District all begin in Arlington. On the map, tot lots, or playgrounds, are identified by a baby in diapers.

The materials obviously were designed to attract families to buy or rent in Arlington, according to Libby Ross, a member of the Northern Virginia Board of Realtors.

The campaign is aimed at attracting families with children back to Arlington, Whipple said. Two years ago, she convinced other officials that something needed to be done to halt what she called a decline in the county's population of children.

According to county planning division estimates for 1980, the latest figures available, one-person households dominated Arlington, with more than 40 percent of the population living alone. Two-person households accounted for another 34 percent, while three-person households numbered only 13 percent. Four-person households, once the size of the traditional American family, accounted for only 8 percent, while households with five or more persons represented 5 percent.

"I was struck by the number of one- and two-person households. I don't want Arlington to become an adult community by default," Whipple said this week. She said she was not deemphasizing the importance of the county's elderly population or its senior citizen population by emphasizing the need for more families in the county.

In 1983, the Arlington Board appointed a task force to study ways to attract families to Arlington. The group that produced the latest package of promotional material is an outgrowth of that task force. As a result of the 1983 action, Arlington also instituted a series of other incentives designed to preserve existing single-family neighborhoods while stimulating development of town houses and apartments. Whipple said finding land to build the traditional tract development is out of the question in Arlington today.

In recent years Arlington has experienced a boom in apartment construction, Whipple said. She cited a long list of new developments, including the 500-unit apartment development known as Randolph Towers now under construction near the Ballston Metro station and a 900-unit development near the Courthouse Metro station.

This week Giuseppe Cecchi, president of International Developers Inc. (IDI), and Clarence Dodge Jr., chairman of the board of Weaver Bros. Inc., announced plans to develop a mixed-use project at the Ballston Metro station site that will include 290 condominiums.

Arlington, Whipple said, has developed density increases as incentives for developers to incorporate residential units in projects near Metro station sites.

In contrast, in nearby Fairfax County -- Arlington's chief competition in the single-family-home market -- officials are still struggling to come up with plans to guide development at Metro stations.

"For a small county close to the center of urban life, Arlington has a remarkable variety of housing -- grand colonials, family-sized ramblers, garden apartments, bungalows, condominiums, duplexes, town houses and high rises," according to the package prepared by the task force. That information is entitled "Arlington Virginia . . . Your Family's Best Move."

Ross and other agents said Arlington is probably best known for its two-story center-hall brick colonials, which are found in almost every corner of the county. In some neighborhoods those homes are lined up like soldiers, all looking alike. But additions and renovations in recent years have dramatically changed some of those houses and doubled their square footage. Those houses sell extremely well to singles and families alike, statistics show.

"There are more colonials and in-between colonials in Arlington than anything else," said Ross, a Town & Country agent in Arlington for more than 15 years. She was on the committee that produced the latest promotional package.

Arlington also has its share of ramblers, big and small, and luxury homes, some in the million-dollar range and more modest ones selling for $300,000 to $700,000. They can be found overlooking the George Washington Parkway and in such neighborhoods as Country Club Hills and Chain Bridge Forest off Glebe Road.

According to Whipple, Arlington has as many jobs as people. "There are 153,000 people employed in Arlington and a population of about the same," Whipple said.

According to county statistics, the 1983 median household income in Arlington was $28,724, while the median family income hit $38,404. In 1980, 36 percent of the residents were single and 46 percent married.

Agents said part of the problem in keeping families in Arlington has been that many families want to to buy newer or bigger houses than they can afford in Arlington. One agent said she had sold a house in Fairfax to people "I know who will move back to Arlington when their children get to college. They just needed a bigger house."

However, young families are increasingly attracted to Arlington because of the convenience to the District and jobs, officials say. "I think what we have is a turning around in housing needs when both parents in a family work. The houses in Arlington suit the needs of the working family better than houses with bigger yards. The short commuting times are also attractive," Ross said.

"They don't want to waste time commuting because they want to spend that time with their children," Ross said.

In addition, everyone in Arlington is within walking distance of either a big or small park, Whipple said