Four years ago Clara Harris took a good look at her increasingly cramped row house off Alabama Avenue in Southeast Washington, the liquor store, fast-food joints and worn apartments down the block in what once had been a quiet, middle-class neighborhood, and told her husband that it was time to move.

Sidney Harris was willing enough, but when his wife carefully laid out her dream of a den, garage, fireplace, and enormous back yard, he got nervous. "I'm not moving to the suburbs," he said. To move from the District to Maryland or Virginia would mean being too far from work, family and friends, and living in a place with a reputation for making black families like the Harrises feel unwelcome.

Last June, a year after exorbitant housing costs in the District forced them to look outside the city limits for a new home, Clara and Sidney Harris packed the china, the 10-speed bicycles and the pet parakeet into a rented moving van and headed for Hillcrest Heights in Prince George's County. A few miles across the District line they turned onto an L-shaped cul-de-sac called Carozza Court, halted in front of a new, $85,000 brick home and officially became part of a major social movement of the last decade -- the suburbanization of the black middle class.

Today, Carozza Court is home to 20 black families whose new brick ramblers and colonial-style homes are easily identifiable signs of having made it in a world long closed to blacks. They are white-collar workers, mechanics and professionals and their decision to leave the city for this quiet street -- where more blacks now reside than there were in all of Hillcrest Heights 20 years ago -- is an indication of a far-reaching change in the Washington area.

Their movement into the suburbs was made possible only after years of political struggle and warnings of social unrest. And yet the actual settlement of neighborhoods such as Carozza Court has taken place in much the same manner of other ethnic groups -- the Irish in Boston, the Italians in New York, the Pols in Chicago -- with neither the dire predictions nor the promises fully met.

For decades only young, white families moved out of the cities and into the suburbs in search of affordable homes, good public schools, peaceful and safe communities. But the pattern changed dramatically during the last 10 years as substantial numbers of black families, most with middle-class values, goals and incomes, began to pursue a suburban life style previously restricted to whites.

In major metropolitan areas across the nation -- from Atlanta to Cleveland to Los Angeles -- 1980 census figures have documented the trend. But nowhere, according to census bureau officials, has the black migration to the suburbs been more apparent and more rapid than in the shadow of the most affluent black population in the country.

Ten years ago 25 percent or 179,000 of Washington-area blacks lived in the suburbs, many of them poor. Today, the suburbs are home to more than 404,000, or nearly half the blacks in the area, and most of these new migrants have incomes that qualify them as middle class or more. At the same time, the District's black population dropped for the first time since the Civil War era, a cause for some consternation among city officials faced with the continuing loss of the District's traditional middle-class core.

As one planner put it when he got the first reports of the 1980 census figures: "The old equation of blacks and urban just didn't stay constant."

Social scientists give many reasons for the break in this equation -- 1960s civil rights legislation made housing discrimination in the suburbs illegal, affirmative action policies brought blacks into better paying jobs and more affluent life styles and the deterioration of many traditionally black city neighborhoods forced middle-class blacks to move out.

The analysts and the 1980 census figures show that the change is happening, but only families like the Harrises and their neighbors on Carozza Court can show how and why.

In describing their experiences it is clear that the transition from city to suburb is not always an easy one. Fear of the unknown often gives way to a sense of isolation, and the old ties -- to churches, neighborhoods and friends -- are hard to surrender.

"This is Maryland," says Tim Alexander, 25, of his home on Carozza Court, "but I think of it as an extension of D.C. I think of myself here as part of D.C."

When the Harrises moved in last June, they were the last arrivals on a street that did not even exist until four years ago, when it was bulldozed into a hillside and named after Anthony Carozza, the Washington developer who bought 800 wooded acres in Hillcrest Heights in the 1940s and developed the area as a suburb.

The Hilcrest Heights neighborhood today is a quiet enclave of rolling residential streets, prim churches and carefully manicured lawns wedged between Iverson Street on the east and Sourthern Avenue at the District's border on the west.

The homes on Carozza Court were built just over two years ago and still bear the stark signs of being new -- sod lawns, uncracked, weedless sidewalks and recently planted maple saplings too young to produce shade or cover the lawns with leaves in the fall.

Most of the 20 families on the street came from the District, primarily the nearby black southeastern section; two-thirds of them work for the federal or District governments and Metro in jobs ranging from supervisor of white-collar workers to bus mechanic; they earn combined family incomes between $30,000 and $65,000, and all of them are black.

There is Gussie Washington, 37, and her lanky, gravel-voiced husband Robert, 49, who left the District 16 years ago because it was getting too "ratty"; Tim Alexander and his fiancee Lulu Hester, both 25, and the owners of the first pool on the block; and Sharlene Williams, 37, and her husband Vernon, 37, returning to the Washington area after two decades of living in all-white suburbs and cities.

In 1960 only 27 of the 13,885 residents of Hillcrest Heights were black. Most black families living in the local suburbs then were either farm workers or residents of the area's few carefully delineated black neighborhoods.

But in the next few years the first few black families began crossing Southern Avenue. Robert Washington was part of that first ripple into the suburbs, a sort of black pioneer -- though he would not look at it that way -- at a time when the suburbs were a ring of white around a majority black city. He makes it clear that he has no regrets.

Robert Washington went out to the suburbs in 1965, not long after he first came to the city from a Virginia farm and the Navy, and landed an $82-a-week job at NIH. Like Sidney and Clara Harris 15 years later, he left the city because it was too crowded, his Northeast apartment seemed too small and his neighborhood, once middle class and integrated, was going down.

Urban renewal, which eliminated many Southwest black neighborhoods, had filled the homes and apartments near him with dozens of poor black families. Like the white families who nervously left Southeast when poor blacks moved in, Washington was uncomfortable with his new neighbors: "I shouldn't say this, but they were undesirables and I just couldn't take it."

His aspirations were like those of millions of others who have moved to the suburbs since World War II, looking for a quiet, crime-free environment.

Washington had no specific place in mind when a real estate agent suggested a $16,500 house in Hillcrest Heights. He hadn't considered the suburbs before but this place was in a nice, well-kept neighborhood and he bought it. When he and his wife moved in, they were the second black family on the street.

It took the better part of the 1960s, a decade of open-housing laws, civic activism and some racial steering before the Washington family was joined by many blacks. By 1970, Hillcrest Heights was 14 percent black. wTen years later the figure was 67 percent, as middle-class blacks flocked into the close-in suburbs of the District, replacing white families.

Last year Washington and his wife Gussie decided once again to move. As before, his neighborhood was changing. Once all white, it was by this time mostly black, with many families from the city. Houses sometimes weren't painted enough and cars were jacked up at the curb.

And neither Robert nor Gussie Washington liked it. "If a neighbor doesn't keep his place up it brings yours down," Washington said. Besides, they had recently sold Gussie's old house in town and it seemed time to invest their money in a better setting.

In early 1980 they went to see the homes on a new street nearby. Carozza Court wasn't finished but the Washingtons felt it had a certain grandeur -- some homes had front pillars; the back yards were big; every house had a driveway. At night you could see planes taking off in the distance and hear only crickets "singing you to sleep," Gussie says.

That March the Washingtons moved into their two-story, pillared house. They loved the oak floors, the paneled downstairs den and the gently sloping yard, which they quickly fenced in and equipped with a Weber grill.

Their only worry, in fact, was who would be their neighbors in the unfinished homes. But, Gussie said, "with the prices of the houses [then around $80,000] I figured the people who moved in would be middle class or upper."

The search for the right environment in one way or another was what brought everyone to Carozza Court. But unlike Robert Washington, most of them moved to the suburbs recently.

Of the 20 families on Carozza Court, half left the District in the last two years to move to the street. Seven lived in other Prince George's County suburbs for a few years before moving to Carozza. Two families came from out of state but in both cases at least one family member had grown up in Washington. One family moved to Carozza from a military base.

Regardless of when the families came, the move was preceded by months, sometimes years of agonizing over whether the suburbs were right for them, whether they would feel comfortable and be accepted and whether they would be too far away from the District, the social and work center for blacks in the area. And when they finally picked Carozza Court, some of them made special late night and early morning trips to the neighborhood just to see if it was really as quiet and conservative as it seemed.

Sidney Harris, who moved in last June, remembers debating the issue for more than a year. And when he finally began looking in the suburbs -- in Camp Springs, Springfield and Tantallon -- he found problems with all the houses. This one was all-electric, that one had poured cement floors. Another was too far away, he grumped to his wife.

"I was looking for any justification," Harris said recently as he sat at the kitchen table after coming home from his job as a supervisor of painters at National Airport.

Harris admits that much of his initial antipathy toward the suburbs was the result of having grown up black in Washington and having always thought of suburban Maryland and Virginia as white enclaves that were not very hospitable to blacks.

"There's always been a different opinion [by blacks] of Virginia and Maryland," he says. "Virginia is the old way of life. If you went over there you worked for Mr. Charley. When you came out to P.G. County you got low-rated, got called names or kicked in the fanny." While Harris says he was willing to live anywhere, the District to him was the one place where "you don't have to look over your shoulder and walk with caution" if you're black.

The same point was mentioned by other families as well, although in careful, often circuitous ways. One man said he didn't consider Virginia because of its "peculiar" laws; others said they vetoed Montgomery County because the county taxes were higher than Prince George's (they're not). In June Allen's case it was her children who balked most three years ago at considering the suburbs: "They didn't want to go from city life to suburban life. They had concerns about going to an integrated school. It was very difficult to leave [but] in order to buy a home, that was the price we had to pay."

The Harrises finally decided to come to Carozza Court after three other deals in the District fell through. The last one was a lovely home in an affluent black section of Southeast. It was surrounded by woods and Harris' wife, who grew up on a farm in South Carolina and had for years wanted a more spacious yard and house, loved it.

But that prospect also soured and Clara Harris firmly suggested that it was time to reconsider some suburban possibilities. They returned to one and then another, eventually ending up on Carozza Court. "I finally said, 'Okay, you like that one? We'll get it,'" Sidney recalled. And with that the Harrises arrived in the suburbs.

Most of the families on Carozza Court made a similarly careful search of the area -- the Gold Coast, Fort Dupont Park, Fairfax Village -- before reluctantly concluding that prices for acceptable houses in town were simply too high. The only way they would get the yard, house, amenities -- and neighbors -- they wanted was to go to the suburbs.

Tim Alexander, a Metro mechanic, made this discovery rather quickly in mid-1980 after his fiancee Lulu Hester called from New Jersey to say that she and her two children by an earlier marriage were coming down to live with him.

"I grew up in the District and that's where I wanted to live," said Alexander. The only reason he is on Carozza Court today is because desire and income didn't mesh. An affordable town house off Southern Avenue was fine for two people, but with the two children its postage-stamp back yard was too small.

Carozza Court, on the other hand, was only $80,000 and it had a yard big enough for the pool Alexander always wanted (which quickly became the envy of the block when he put it in) and space left over for a fenced-in play area for the children. But most important, it was close to family and friends in Southeast Washington.

A major reason Prince George's County has been so attractive to black families, in fact, is its location adjacent to black sections in the District.

While nearly half metropolitan Washington's black residents now live in the suburbs, 61 percent of them -- some 247,860 -- live in Prince George's County, accounting for 37 percent of the county's population. Two-thirds of these new families are middle class, according to 1977 census data analyzed by the Grier Partnership, Washington-area demographers.

Once a substantial black community was established in Prince George's County, it became an even more attractive place for black families who wanted to move to the suburbs.

Vernon and Sharlene Williams are perhaps the best example of a black family moving to the suburbs in search of a black, middle-class neighborhood. "My daughters have never been in a predominantly black area, a black and middle-class area and we wanted to expose them to that," said Vernon Williams, an analyst with the federal government, as he ate Gouda cheese and sipped white wine.

For 20 years, as Williams pursued a career with the Mobil and Gulf Oil companies the family lived in one white area after another -- Queens, N.y., Montclair, N.J., Cannonsburg, Pa.

Although Williams says it did not bother him, his wife and especially his three daughters found it difficult at times to live in white areas.

When the Williamses came to Washington in 1979 to be near Sharlene's family, they were looking for the "right" black neighborhood, where their neighbors wanted the same things from life -- education for the children, a decent income, a well-kept neighborhood.

They quickly focused on a few places in Prince George's, where Sharlene's parents and two married sisters had moved within the last few years. A real estate agent took them to Hillcrest Heights, and on a typically steamy summer day they moved into a house on Carozza Court next to Robert and Gussie Washington.

Sharlene Willaims looks back now with some amusement at her daughter's desire for a black middle-class neighborhood. "Once they got into the 'right environment' they thought they were going to party all the time," she says, snapping her fingers over her head. "But what they're finding out is that black neighborhoods are just like other neighborhoods."