A quarter of a mile north of the Town Hall that locates the center of Needham , carpenters, electricians, and plumbers are finishing off a row of buildings identified by the sign in front as ''The Highlands: A Luxury Condominium Community.''
Beneath the foundation of the Highlands may lurk an old brick or two from the edifice leveled to make way for the new condos - Highland Elementary School.
Less than a mile away, more construction trucks surround a large red-brick building. Carved indelibly on the front is: ''Avery School.'' But a sign on the front lawn reads: ''Avery Park: A Condominium.'' For prices ranging from $85,000 to 55,000, buyers of the 24 units can choose an apartment in the one-time school or in a three-story addition that now covers the old playground.
These metamorphoses - from school to condominium - in this pleasant suburb 10 miles southwest of Boston dramatize the radical change besetting the American suburb during the 1980s.
Everywhere schools are closing as the birthrate drops. The no-pets, and sometimes no-children, condominiums and town houses replacing them cater to an older suburban population, mixed with a growing number of singles and those once married. Like many long-established suburbs, Needham now has more residents over 60 than school-age children.
The sound of hammers at the Highlands and Avery Park also signals that the balance between single-family homes and multiple units is slowly but steadily shifting.
Above all, some old sense of permanence is gone. When the townspeople of Needham built their ''modern'' schools after World War I, they thought they were forever. The developers now replacing blackboards with vanity mirrors and teachers' desks with kitchen counters can have no such illusion.
The American suburb is far from one homogeneous entity. But the one thing every suburbanite in every suburb across the country is sure of is that his or her community has been changing - and is going to change more - and that the pattern of the future is by no means clear.
''What you're dealing with is a complete revolution,'' says George Sternlieb, director of the Center for Urban Policy Research at Rutgers University.
A revolution is not exactly what is wanted by the 43 percent of Americans who live in the suburbs.
To find the ideal that lies behind a New England suburb like Needham, a visitor must return to that red-brick Town Hall with its gilt-domed clock tower, serenely overlooking the town green with all the authority of a building dating back to 1902 - and representing a town dating back to 1711.
The green in front of the Town Hall gives the vestigial feeling of a village green. The town's old-timers remember when a blacksmith's shop stood within a stone's throw of the building.
One could not travel more than a few blocks in any direction beyond the clustered new houses of half a century ago without coming to farmhouses and barns and apple orchards. A half mile from the square, cows grazed in fields for a dairy that made deliveries by horse and wagon.
Needham in those days was like a stage set for two different plays, satisfying sociologist Philip C. Dole's definition of the suburb as ''the middle ground between nature's beauty and civilization's convenience.''
Far from being a revolution, the traditional New England suburb like Needham has promised a special kind of stability that the volatile city could not offer - with its slums, its smokestacks, its hurly-burly violence - and a convenience the authentically rural could never supply.
When Needham commuters of 50 years ago disembarked from the Boston train at night, carrying rolled afternoon newspapers, they came to a clean, ordered place. They strolled home, two by two, along tree-shaded streets, past the white-steepled Baptist church, or the red-brick Stephen Palmer Grammar School. The lawns were neat, the hedges clipped, the sidewalks smooth and clean for mothers with baby carriages.
Was this a myth, even in its own time? Of course. But it was the American Dream, as much as anybody understood it.
The turning point was World War II. In 1940 Needham numbered about 12,500 inhabitants. That figure more than doubled in the 30 years that followed. To make room for those 16,000 extra townspeople, woods were cleared and pastures were plowed into lawns. A pig farm was reclaimed. Blacksmith's Pond, where the old-timers skated as children, was filled in and built upon.
By 1952, when Broadmeadow School was constructed, Needham neighborhoods rang with the voices of that most famous group of American offspring, the baby-boom generation. The parents of those children, aided by VA loans and FHA financing, settled into the Capes and colonials on Bird's Hill, where young lovers (now grandparents) used to watch the moon.
The quandary of the suburb is that of the tourist resort: The unspoiled charm that attracts people in the first place becomes a casualty of its popularity.
John Milligan, a real estate broker and Needham resident for 28 years, says: ''The biggest change I have seen is walking downtown to the hardware store on Saturday. I used to walk and say, 'Hi, hi, hi.' Now I walk and wonder, 'Who was that? Who was that? Who was that?' ''
''When I moved here,'' he adds, in a classic suburban lament, ''it was a small town. I felt like saying, 'Close the door.' ''
Today the train station in Needham Square - once the pride of the New York-New Haven - houses Compton's Paint Store, and mothers have joined fathers on the commuter buses to Boston. The kaffeeklatsch has moved from the kitchen to the supermarket aisle, where hurried young mothers exchange car-pool schedules and day-care leads the way their mothers once traded recipes.
Molly Shaw, a mother of four, says: ''The biggest change in the neighborhood is that there's no one home. The blizzard of '78 was a delightful time - nobody could go anywhere. Everything slowed down. We became a community.''
The suburbs were built upon the unpaid labor and ubiquitous presence of women - as housewives, mothers, community volunteers. Now the women are no longer there, and this is making all the difference.
In Jo Belval's second-grade class at Broadmeadow, 12 of 22 students have working mothers - a ratio that parallels the national average.
''Six years ago,'' she recalls, ''you would ask for parents to chaperone a field trip or to be room mothers, and you'd have plenty of volunteers. No more. It's not that they don't want to, they just can't.''
Mrs. Belval worries about the effects on children. ''Some younger children are going home to an empty house, because baby sitters are expensive,'' she says. ''I really feel for some of the children who are bearing the brunt - they just can't handle so much responsibility so young.''
If ''togetherness'' was the rallying cry of the '50s, ''apartness'' threatens to be the fact of the '80s.
''People aren't entertaining as often,'' says Sandra Mangine, who has lived in Needham since she was 9. ''We live too fast. We're running, running, running. Most social gatherings turn out to be meetings.''
Meetings to discuss, in one way or another, the Suburban Situation. ''The suburb,'' social historian Lewis Mumford once complained, ''was a pharasaic way of passing by on the other side.'' Now there is no other side. For the suburb has inherited most of the urban problems it was set up to distance itself from. ''Alcohol-related arrests numerous'' reads one headline in a recent issue of the Needham Times, one of some 1,700 suburban newspapers in the country. ''Rash of vandalism incidents reported'' another story proclaims.
Traffic jams stack up Needham Square as residents, shopping lists in hand, follow what Mr. Milligan describes as ''the order of business on Saturday: People go to the dump, then they go to the hardware store.'' Nobody knows where to park all the cars that make the suburb logistically possible.
Once the major complaint about the American suburb was its style - conformity and a certain blandness. Now the challenges are more tangible - and often involve money.
Suburban dwellers in the halcyon days of the '50s and '60s can recall when the expansive mood of the times was mirrored in two words: ''Vote Yes.'' School bond issues passed. Services increased. Nothing was too good, it seemed - or too expensive - for the suburbanite's children, or, in fact, for the suburbanite.
Today the dictum is: ''Vote No.'' In Needham, as in other Massachusetts towns , residents are bracing for the third year of cutbacks mandated by Proposition 21/2, a statewide property-tax-restricting measure. School appropriations for 1984 are being cut by $124,775.
''This is a very tight budget,'' the Finance Committee admits in its annual report, explaining the need to trim nearly $1 million in appropriations. Those cuts, the committee warns, ''may affect the quality or quantity of services and programs.''
Marcia Carleton, one of five town selectmen, confesses: ''I spend my whole life, it seems, talking budgets. We're cutting services just at the time when our population is getting older. Some towns are thinking of dropping garbage collection, for instance. But the little lady who can't get to the dump, what does she do with her garbage?''
One service recently rescued from an uncertain future is the Needham-Mite minibus. After considerable debate, Town Meeting members voted to increase funding and restore summer service.
Noting that one-third of riders are senior citizens, Mrs. Carleton points out the importance of the minibus: ''Many women my mother's age didn't learn to drive. Now they're alone. Can you imagine never getting out of this house unless somebody offered to pick you up?''
The service is also important to another group heavily dependent on public transportation: the students who now make up half of the minibus riders. ''They're too old to need baby sitters and too young to drive,'' one planner says, echoing the humorist Peter DeVries, who wrote: ''A suburban mother's role is to deliver children obstetrically once, and by car forever after.''
''People forget that a lot of mothers are working - particularly the single-parent mothers,'' Mrs. Carleton says. ''There isn't anybody to see that those kids get to the dentist and the library and the lesson after school. People aren't admitting that changes in their lives make new demands on public transportation - and a lot of other services.''
Yet, she admits, ''Proposition 21/2 isn't all bad. It has made everybody relook at things.''
Like every American suburb these days, Needham has a new master plan to meet all these situations old Needhamites could never imagine. Sometimes zoning laws - the sacred cows of the suburbs - become involved.
In a town where more than 98 percent of residents own their own homes, approval of zoning changes may not come easily. ''We're not unique in Needham,'' Mrs. Carleton says with a laugh. ''We resist things the same way every other town does.''
Some of that resistance surfaced last year during construction of Cooke's Bridge, a $5 million, federally funded low-income housing development nestled in a hollow near the Needham-Wellesley line.
''People were strongly opposed,'' says Rita Osborn of the Needham Housing Authority. ''It's like building a jail next door. They say, 'Build it somewhere else.' '' Yet so desperate is the need for low- and moderate-income housing in Boston suburbs that some 150 people waited all night in a November rain to apply for quarters in the 76-unit complex.
This ''not on my block'' attitude knows no regional bounds. C. Richard McCullough, an architect and a member of the planning board in nearby Medfield, explains: ''Every time we see what potential lies on the horizon, we find that rather than necessarily giving it a chance, there's a lot of negativism in terms of, 'I'm afraid to try it. I'm afraid it's going to hurt the value of my property.'
''In the suburbs it is a time of reassessment for more than the property. But the more some things change, the more other things remain the same.
Even the hammers banging away at those school conversions may be premature. ''We're seeing a lot of people buying a house to raise kids in - later,'' says John Milligan, the real estate broker.
Ticking off the latest trends, Robert C. Wood, author of ''Suburbia: Its People and Their Politics,'' told the Monitor: ''In the suburbs there is the leftover of the swinging '60s and '70s - the single heads of households, the divorced, childless, the whole impact of feminism. But at the same time there's a baby-boom echo. Families aren't bigger, but the number of women of child-bearing age now is a much greater part of the population. You'll see the elementary schools start to fill up in about two to three years.''
The sobering but not unexhilarating message from the clock tower in the town square of Needham seems to be a healthy new awareness that the suburb can never be (and never was) an escape clause from life - an Eden free from the dilemmas of the rest of society. Nor should it wish to be.
Mr. McCullough sums up: ''Revolution sounds like an awfully strong term, but we're going through a period of transition where we're searching for answers. I think it's incumbent upon all of us to decide what's in the best interests of our society as a whole, not just how it affects No. 1.''
Tomorrow: Eden Prairie, Minn. -- planing a ''balanced'' community