The evidence: plush living rooms in North Portal Estates, with African wall hangings and smoked-glass coffee tables; crowds of impeccably dressed young professionals comparing BMW keys and tax shelters over happy-hour spritzers along the Southwest waterfront; quiet, stolid, gracefully aging neighborhoods in Northeast, where family and church are more than words on a kitchen cross-stitch; the downtown power-lunch restaurants where a new group of sharp-eyed players convenes to carve up the bast sphere of power and money that has come to center on the District Building.

You can see more on any downtown street, where kids in $75 blue jeans and $50 red-and-black Air Jordan sneakers bustle past businessmen wearing outfits whose labels add up to a short course in Italian; where proud, stylish women sport hundreds of dollars' worth of hairdo, facial and manicure work as they browse through exclusive boutiques; where all around are the sights and sounds of a booming black consumer market that spends freely, buys quality and pays with American Express.

For a big, bold visible part of black Washington, the evidence proclaims, life has never been better.

The problem is that although many have shared in the prosperity, not everyone has. While some blacks in Washington were realizing the American dream, another group -- call it the aspiring black middle class, the Toyota crowd as opposed to the Volvo set -- found it necessary to move away to find jobs, decent housing, better schools and safer streets that had become so frightfully expensive inside the city's borders.

And the rest of black Washington, perhaps as much as a third of it, simply went to hell.

For along with the visible evidence of new black power and affluence in Washington, there are other sights -- harder to spot, perhaps, and certainly more painful to notice -- of slow death.

Sights like the boarded-up storefronts along U Street, once the heart of a thriving black community. Like the chimerical crowds of junkies at 14th and U, a twilight zone where one minute the corner is deserted, and then another minute scores of sullen men and women somehow appear, slinking out of alleyways and apartments and parked cars for the ritual police call "feeding time." Like the slabs of apartments that hug the hills of far Southeast, dreary places where children struggle -- against almost prohibitive odds -- to raise children of their own.

And like the spectacle of nine young men and one young woman, all of them really nothing more than kids, sitting in a D.C. courtroom last year charged with tthe unspeakable murder of a 99-pound, 48-year-old woman who was bludgeoned to death in a Northeast alley while a crowd cheered on her assailants.

These are sights of Washington's "underclass." The term is one of be resisted, because of the hopelessness it implies, but one that seems increasingly appropriate. The situation of these people is getting worse, not better, and no one seems to have any answers.

It was never accurate to talk of black Washington as a single entity. This city was one of the first in the nation to develop a viable black middle class, and there have always been the relatively affluent and the relatively poor here. But 25 years ago it seemed more accurate to call black Washington a community, diverse but with a shared dream.

The dream was of freedom and full equality for all black Americans, and it was a powerful unifier. Now, although no one pretends the dream is fully realized, its sway is undeniably diminished.

Black Washington has fractured into the haves and the have-nots; or perhaps a split more ominous; the already-haves and the never-will-haves. All indications are that the fault line is widening, driven by forces more powerful than all the world's good intentions and racial solidarity -- both of which black Washingtonians have in ample supply. There are no real villains here, just a set of winners and a set of victims.

Blacks in Washington now have a range of options that once were out of the question, from selecting a career to deciding where to eat lunch. The achievement of some self-government is alone a bold achievement, although home rule probably has a lot more to do with how people feel about their citty than whether their garbage is picked up on time.

Remember, until a decade ago residents of the nation's capital had no mayor, no city council, no elected school board; until 1964, they couldn't even vote for president. Now there is a rapidly maturing political apparatus, headed by a former street activistt who has long since shed his dashikis for three-piece worsteds by Yves Saint Laurent. The disenfranchised have become the establishment. Washingtonians still don't have complete authority over their government, but they've come far enough to feel immense pride.

Even more significant is that 25 years ago, no black Washingtonian could escape the simple fact of segregation.

Louis Martin, now a Howard University official, came to Washington in 1960 and stayed to become a kind of black political godfather, or at least a consiggliere, offering sage advice over the years in countless floor fights, court battles and politcal campaigns touching on the issue of civil rights. "I came in with the Kennedy-Johnson campaign," Martin says. "Washington then was a small southern town, that's the way it struck me, coming from Chicago. The segregation struck us all. Opportunities were just dismal for blacks then. You couldn't really enjoy your own city."

Martin recalls urging President Kennedy, shortly after he took office, to make a big push toward integrating the federal bureaucracy.

"I never will forget that one day, Kennedy and some of his aides toured several federal buildings," Martin says. "We went to this one building -- don't recall just which one -- and on the first floor, we saw a few blacks. On the second floor, there were fewer. On the third floor, fewer still. Finally when we got to the top, there were no blacks anywhere.

"Kennedy turns to me and says, "They get whiter the higher they get." The upper reaches of the federal bureaucracy here-abouts still remain mostly white, but Washington's largest employer did become substantially integrated at lower levels, and as federal salaries rose, the well-being of black Washington improved.

Washington's good-ol'-boy business community has been much slower to integrate. Just a decade ago, the Board of Trade had no meaningful black membership; more recently, the entertainment at the Board's annual dinner one year consisted of what looked and sounded to some blacks in the audience like an old-fashioned minstrel show. Attending a board function nowaadays, and watching the red carpet rolled out for Mayor Marion Barry, must be sweet irony for those who remember the days when the white establishment considered him perhaps the city's most dangerous militant activist.

The Board of Trade has seen the light. It now has lots of black members, and it skillfully plays ball with the black political establishment. The city government, meanwhile, has taken great pains to foster black economic development in the city and has had some success.

The truth is, though, that a list of the really important businessmen in Washington would still be almost exclusivly white and male. The late Theodore Hagans was an important developer; William B. Fitzgerald can be called an important banker, and then it gets harder to come up with names of bblacks who have made it in the big leagues of Washington business.

Meanwhile, just as the black baseball leagues began to wither when blacks were allowed into the major leagues, so has Washington's old black business infrastructure weakened and become less important. The D.C. Chamber of Commerce used to be of great importance to black businessmen in Washington, serving the same purpose for blacks that the Board of Trade served for whites. Now, with the Board of Trade open to blacks, the chamber is no longer at the center of things. It still has a lot of members, but basically they are the owners of small businesses. The big black-owned businesses, the ones that would increase the chamber's clout and influence, now can afford to pay the board's dues, and to send their own representatives to lobby the City Council and the mayor.

The two biggest black economic forces in the city remain institutional: the city government itself, and Howard University, which spends $300 million a year and employs 8,000 people.

The barriers that used to keep blacks out of some neighborhoods have come down, but basic housing patterns have not changed, except that once-black neighborhoods like Capitol Hill and Shaw have become whiter through the process called gentrification. One examination of census data showed that during the 1960s, the city's housing patterns actually became more segregated. The part of the city west of Rock Creek Park remains overwhelmingly white; the Northeast and Southeast quadrants remain overwhelminggly black.

These patterns are reflected in the city's public schools, which are now, bu all accounts, on the rebound. The school system went through a kind of cultural revolution during the 1970s, as administrators sought to make them relevant to the black urban experience -- at the expense, many felt, of making them good schools.

First whites fled the school system, then middle-class blacks fled. Finally, the school system began a concerted effort to improve itself and took the position that retaining some of these fleeing students was crucial. Now, as test scores rise under a new back-to-basics curriculum, administrators take unabashed pains to keep white and middle-class black students.

The creation of a new "model" high school, Banneker, reminds some of the days when schools were segregated and the black community had its own superior school, Dunbar. In a sense, the schools have come full circle.

Blacks in Washington are doing very well compared with blacks elsewhere in America. A recent comparison showed more black Washingtonians in high-income groups and fewer in poverty than among blacks in any of a half-dozen cities of comparable size. Income and educational levels here have skyrocketed. In other cities, like Chicago, blacks are striving for political power, here the effort is to consolidate the power and use it for economic development. The confidence of black Washington is such that recently it helped elect a white City Council chairman without undue concern about losing power.

The gains are tangible and real. The losses, less tangible, but no less real, dervice in part from the gains. They come with the turf.

Wealth and power bring complications. Howard University offers an example. For many years Howard has been the nation's premier black intellectual center, but in the past two decades it has grown immensely, its annula budget increasing tenfold. Howard has even substantially bucked the trend afflicting other historically black colleges, still attracting good students and professors despite the lure of bigger, white institutions.

But last year, Howard, the crucible of civil rights law, found itself fighting a "reverse discrimination" lawsuit and arguing in court that it had an effective right to ensure with its hiring policies that it remained a black oriented institution. The campus community was divided over the issue. Years ago, few white academics were interested in working at Howard; today more are, and the school must deal with the price of its success.

The breakdown of segregation in housing has made it impossible to rebuild the commercial strips like U Street and H Street that were dealt a death blow by the riots. These areas, in the days of segregation, had been vibrant, economically integrated communities, places where blacks of all income levels went to eat and be entertained. As blacks began to be welcomed elsewhere, the businesses along these strips began to decline; as middle-class blacks moved out, only the poor were left. After the riots, there was no longer a reason to rebuild. The pattern of blacks patronizing black-owned establishmentts had broken down.

The phenomenon can be seen all over town, as mom-and-pop corner grocery stores, many of them formerly owned by blacks, are bought by Asian immigrants who use them as steppingstones to the middle class. The process brings complications: Is it racist to object to the trend? Perhaps. Is it racist to wish that blacks were reaping the benefits of these little stores? Is there anything that can, or should, be done?

And finally there is the growing isolation and desperation of the black underclass, a group for which the lights seem to dim with each passing year. In 1960, one of every five black households in Washington was headed by a woman. Today, one in two is female-headed. Many of these families include teen-age mothers. A third of all black children in Washington live below the poverty line. The gap between poor blacks and others is increasing -- while one group of blacks gets better educated and more affluent, another group stays poor and uneducated, and has less and less chance of escape.

Gentrification makes fewer neightborhoods affordable for the poor. Government tries to intervene, but for many of the poor there is less and less meaningful contact with the more affluent. Horizons are shrinking, not expanding; and the black family is in crisis.

Washington is far from being the "crime capital" of America, as President Nixon once called it; and crime has been dropping steadily over the past decade. But Washington keeps more of its citizens incarcerated than any other jurisdiction. Washington has a problem of heroin addiction said to be the worst, per capita in the nation. Cocaine is sold openly on the streets in quantities small enough for non-yuppies to afford, and it has found a new market -- and an extensive sales force -- among poor black youths. PCP, an even more insidious and debiliating drug, has taken hold among the city's teens; you can pick the heavy PCP users out of a crowd because they're the ones drooling.

How do you change these people's lives? How do you even reach them? How can a private sector that increasingly needs workers with technical skills do anything for the uneducated? How can a city government, even one with the noblest of intentions, worry about maintaining a tax base and creating a favorable business climate and still wage a determined, lonely, necessarily costly war against poverty?

No one knows the answers. Small-scale successes abound -- a group of teen-age girls is taken in for counseling against getting pregnant; a youngster from Anacostia is accepted at Ellington, the high school for the performing arts, and turns out to be a prodigy; a youth parlays a summer job into a career, but the problem has been growing, not shrinking.

"Three decades ago, Constance M. Green wrote a seminal book about black Washington called Secret City. Today, most of black Washington has emerged into the light. But there is a new invisible Washington, and the good life that most of us share has passed it by. The years have been good, not kind.