Not too long ago, Arlington County Board member Mary Margaret Whipple asked a man she had just met if he lived in Arlington.

"No," he responded. "I live in Rosslyn."

The reply was perhaps an odd one from an Arlington resident. But for many people who live outside the county, the high-rise enclave on the Potomac River across from Georgetown long has been regarded as a neighborhood with an identity of its own, and a rather desolate one at that.

Since the first high-rise buildings went up in Rosslyn in the early 1960s, the area has been the butt of "tumbleweed" jokes, references to its ghost town eeriness after the office workers head home at dusk, abandoning Rosslyn to a few cars passing through and a small contingent of residents who rarely ventured out at night.

The problem with Rosslyn, county officials have long recognized, was that office buildings were given preference over residential buildings. And with few residents, there was little need to provide the kinds of stores that sustain residential life or attract nonresidents.

Slowly, almost imperceptibly, that has been changing. Rosslyn has been undergoing a residential face lifting -- a nip of town houses here, a tuck of condominiums there. During the past four years alone, the County Board has approved almost 1,200 residential units that have been built, are under construction or soon will be -- more than doubling the residences there.

Soon, developers say, some of the office workers who head home to other suburbs will not have to because of the new residences that will ring "downtown" Rosslyn.

"There is ample evidence that the Rosslyn residential market is definitely on an upswing," said Thomas C. Parker, the county's economic development chief. "This is a welcome change," Whipple agreed. "I don't know that I would classify this as a dramatic change, but I do think it's going to make quite a change."

Accompanying this trend, in part inspired by the improved economy, is the beginning of a Rosslyn renaissance that few county officials spoke of a decade ago. While it is still far from being a teeming area after hours and on weekends -- most county officials doubt it ever will be that -- the signs of a reawakening are there.

Already, developer Edward L. Daniels said: "People are staying in Rosslyn longer. It's not the old mentality of getting into your car and getting the hell out of Rosslyn at the end of the day."

John Attus, one of the owners of Tivoli's Restaurant, says he can see a change in Rosslyn in the two years since the restaurant opened. "It's much better in the evening now," he said. "You can see there is something going on more than usual around Rosslyn. The streets used to be dead, but now they're more lively."

Inspired by Rosslyn's hillside location, which provides post card views of Washington, and by the presence of a Metro station in the area's center, developers say they are pitching Rosslyn as the place to live for comfortably retired empty-nesters and upwardly mobile young professionals.

Home sales have been brisk, some developers say, even with prices reaching as high as $428,000, partly because of the District's attractions just minutes away and Arlington's low real estate tax rate.

"People can get the feeling: 'I'm out. I've crossed the line into Virginia, and yet if I want to go to Georgetown or K Street, I can be back in there in five minutes,' " said Daniels, vice president of Clover Development Corp. His firm is building the $20 million, 239-unit Astoria condominium complex on Lee Highway within sight of Rosslyn.

While the complex is closer to the Courthouse Metro stop, Clover is marketing the Astoria as a Rosslyn residence. "We'd prefer to align ourselves with what's a fact," Daniels said. "Courthouse doesn't have the present level of restaurants and amenities" that Rosslyn has.

Barbara Everett, a real estate agent for the 20-unit Dundree Hill condominium not far from the Astoria, says they are also stressing the Rosslyn connection. "They wanted me to use 'Arlington,' but I said: 'No way. We're going to advertise this place as Rosslyn . . . . Residents will have Georgetown right next door; this will be an extension of Georgetown as far as their life styles are concerned.' "

Visitors to the model units of the $60 million Belvedere luxury condominium in Rosslyn are shown a movie about the 562-unit, Renaissance-style complex being built by Giuseppe Cecchi's International Developers Inc.

"People of vision look for sophistication . . . look for a new city of their own, and that's Rosslyn," the movie narrator says as scenes of "has-it-all" Rosslyn appear touting recreation, dining and shopping facilities in Rosslyn, and the proximity of Georgetown across Key Bridge.

Cecchi, developer of Washington's Watergate complex, was one of the first developers to revive the Rosslyn residential market when he sought approval of his Belvedere plans three years ago. "Nobody wanted to touch Rosslyn because Rosslyn had the connotation of being dead at night," he said. "It was so empty, the place was almost scary."

An advocate of mixed-commercial and residential developments, Cecchi says that the Belvedere's five-acre tract provides an excellent opportunity to respond to the demands of office workers for nearby homes. The site is just a few blocks from the subway and provides panoramic views of Washington, he says.

Cecchi works in Rosslyn directing his operations from a 19th-floor suite in his Rosslyn Center building, which is a center of activity. It contains dozens of shops, boutiques and Tivoli's Restaurant above the subway stop. It was because of Cecchi's personal prodding that the Watergate's chef left Washington to open Tivoli's, a gamble at the time.

Since then, Cecchi said, "Life has changed tremendously here. People are using the shops. Four or five years ago, there wouldn't have been a quality restaurant here attracting people from Washington." Now a second "white tablecloth" restaurant is on the way, planned for the second tower in the USA Today complex.

"Rosslyn is a proven location," he said. "You can't go wrong with Rosslyn. You'd have to make a really big mistake to go wrong in Rosslyn."

When Cecchi looks out his window at other potential sites for residential development in Rosslyn, he says there is room for more housing. "With that, Rosslyn will have enough population here to generate business potential for more shops and restaurants," he said. "The day businesses will extend more and more into the nights and on weekends. It's going to happen over the next five to six years."

That is a goal the county government has been working toward for more than a decade. The County Board has firmly rejected plans to allow offices at sites designated for hotels or residences, and it has made retention of neighborhood stores, such as supermarkets, a top priority.

Two weeks ago, the board agreed to give a proposed Rosslyn office building extra density because of the developer's pledge to take steps to keep a supermarket at the site, now occupied by the Rosslyn Safeway.

"We'd be very upset if they didn't keep a supermarket there," said F. Pearson Ames, vice president of the Knightsbridge Development Co., which is building The Atrium, a 325-unit luxury condominium at North 18th Street and Key Boulevard. Ames says the firm scrapped plans to put retail businesses in the $50 million project because the site is adjacent to the Safeway.

County planner Robert Brosnan says the staff also is trying to "hold the line on conversion of restaurant space to office space. We need to keep restaurants or some kind of retail there because, although they may have trouble renting the retail space there now, we're never going to get it back to retail once it goes office."

"I think we'll also find," Brosnan added, "that as Rosslyn gets ringed by more residences, the area will start having more retail because people will be clamoring for it, demanding it."

County Board Chairman Ellen M. Bozman and board member Whipple note that the county has other plans to make Rosslyn a more vital place and to alter some of the negative perceptions about the area. The plans range from the completion of wide sidewalks with planters, to a landscaped park with an outdoor theater over Interstate 66 at Rosslyn Circle.

Still, Bozman said she doubts that "Rosslyn is ever going to be teeming with people at night . . . . The only time you'll have that is when you have the kind of nighttime activities that bring people out -- more restaurants, theaters, bowling alleys or whatever brings them out."

Sami Totah, a partner in Quad of Arlington, which is building The Cascade, a $16 million, 184-unit rental building at 1550 N. 17th St., joins other developers in complaining that the county has not been aggressive enough in its quest for residential construction.

But if the county continues to push for more stores and other improvements, Totah said: "They can give Rosslyn a cachet. It won't be Georgetown, but they can give Rosslyn a cachet which will make it very attractive."