After years of being snubbed in favor of communities farther from the city, Washington's closest suburbs -- those inside the Beltway -- are coming back.

Preliminary 1990 census figures released recently show that Alexandria, Arlington and the inner Maryland suburbs, whose populations nose-dived in the 1970s, either stabilized or grew during the last decade.

"The growth of the area has sort of turned inward again," said George Grier, of the Greater Washington Research Center. "A lot of these inner suburbs aren't going to be quite the geriatric areas we thought they'd be."

Their population gains, typically less than 10 percent during the decade, still do not match the booming growth of the outside-the-Beltway suburbs. Those outer areas continue to accumulate political clout and tax base -- and problems in meeting the demand for public services.

Among the outer suburban areas, Loudoun and Prince William counties in Virginia, for example, grew 49 percent in the 1980s. Howard County in Maryland expanded 57 percent.

But the quiet resurgence of the core suburbs means that schools there are filling up again, tax rolls are growing and new houses are being built, a few at a time, on once-vacant lots.

One reason for the change is that a wave of foreign immigration has pushed population growth faster than had been forecast.

"We had anticipated a flow back in, but more toward the latter part of the '90s," said Stuart Bendelow, of the Maryland-National Capital Park and Planning Commission.

The preliminary census numbers released last month include totals only for incorporated counties, cities and towns and are likely to rise when final figures are published next year. Figures will not be available until then for areas such as Annandale in Fairfax County and Bethesda in Montgomery County, but local planners say those statistics also will confirm the inside-the-Beltway growth in the last decade.

For some, getting bigger gives a psychological lift.

"You get a feel of movement," said Condie Clayton, city manager of Mount Rainier, which lost 10 percent of its population in the 1970s and gained back 7.6 percent in the last decade.

Built as a working-class suburb, Mount Rainier is spiffing up: City Hall is expanding, a historic district has been proposed and an anti-crime task force has been created.

Seat Pleasant Treasurer Robert Ashton is happy too, because he thinks rising state income tax receipts from his city and the declining number of houses being sold to pay back taxes indicate that growth is bringing a more stable, higher-income population. "We are attracting a different type of people," he said.

Many of the inner suburbs grew quickly in the Baby Boom of the 1950s and 1960s. But in the following decade, children grew up and left home, birthrates dropped, housing prices rose beyond the incomes of young couples, and some white families fled increasingly black areas.

During the last decade, according to demographers and public officials, those trends eased or bottomed out, part of a typical pattern of neighborhood ebb and flow.

"If we kept losing like we did between 1970 and 1980, our average household would be less than one in a couple of decades, which is impossible," said Ralph Rosenbaum, a senior planner for Alexandria.

A new wave of foreign immigration has intensified the growth. Thousands of Asians and Hispanics are moving into lower-priced houses and apartments, sometimes crowding large families into apartments formerly occupied by one or two people, according to local officials.

"That's who's making a difference in the school population," said Margaret Simkovsky, research coordinator in Arlington County's Planning Division.

After losing enrollment for years, the Arlington schools are expected to grow slightly during the next decade. The same trend that is once again filling classrooms could result in new costs, however, because foreign-speaking students generally are more expensive to educate.

In the typical neighborhood life cycle, older couples with grown children sell the houses where they have lived for several decades to younger families. Simkovsky saw that happen on her block, where most of the eight 1950s homes were held by original owners a few years ago. Now, all but two have changed hands.

Such turnover was accelerated here by the booming real estate market of the late 1980s, which tempted more owners to sell, planners say.

The legendary traffic jams and rising prices of the Washington exurbs made closer-in locations more attractive. The under-$100,000 neighborhoods were still affordable, and the more expensive inner areas once again lured buyers because prices outside the Beltway were no longer so much cheaper. The Metrorail system, extended to the suburbs in the late 1970s, also helped.

"The commute that goes with moving further out has probably put additional pressure on the close-in suburbs," said William O'Hare, director of policy studies for the Population Reference Bureau. "Looking ahead to the '90s, these inner suburbs could be even more attractive."

Although neighborhoods such as Alexandria's West End have added thousands of new houses and apartments and several large projects are underway in Prince George's County, much new construction is limited to a small parcel here and there.

Plummeting birthrates in the 1970s were reversed in the last decade, both outside and inside the Beltway. Births in Montgomery County, for example, have nearly doubled since their low point in the mid-1970s, especially births to women 30 and older. In Fairfax County, the birthrate pushed up average household size in the mid-1980s for the first time in two decades, according to county officials.

The growth of the inner suburbs is unlikely to be big enough to require new school buildings, but it will translate into millions of dollars worth of additions to existing ones, some in areas where schools were closed 15 years ago.

Six of the 10 elementary schools that feed into Montgomery Blair High School in Silver Spring will be over capacity by the middle of the decade. In the last two Fairfax County school bond referendums, more than half the proposed additions were in older neighborhoods.

The same is true in Prince George's County.

"We were so overcrowded last year that they took 150 kids away from me," said Hyattsville Elementary School Principal Emidio Cicolini. "The birthrate is really controlling population in this area."