IN Paris's 20th arrondissement, a working-class rim of the city, immigrant families return to their apartments after vacations to find their furniture and other belongings thrown out of the windows to the courtyard below. The building's new owner wants to renovate it for higher profit, and so strong-arm tactics are used to get the renters out. Not far away in a dilapidated 170-year-old neighborhood called the Goutte d'Or (the ``drop of gold''), Khiter Zaidi, a tile layer, spends his days putting finishing touches on expensive new apartments. He wonders how much longer his family can stand the 120 square-foot room they have been renting for 12 years.
The neighborhood is undergoing a major renovation project, and as Mr. Zaidi notes, ``The city says they want families to live here.'' But the Algerian and father of four says what is being built is either too expensive or tacitly off limits to immigrants. ``There's no place left here for families like mine,'' he says.
Farther north in Montmartre, at the front steps of Sacr`e Coeur Basilica, Mediba Sankar`e camps out with his and eight other families in a tent they have kept there for 92 days to protest the lack of affordable housing in Paris.
``I have lived in Paris for 27 years,'' says Mr. Sankar`e, who was routed from his building 10 months ago when the city said it was about to collapse. Since then, he has found nothing.
``We feel this neighborhood is our home,'' says the print-shop worker, ``but it doesn't seem to have any more room for us.''
These families, all of whom pay their modest rents faithfully, are discovering what thousands of other poor and working-class families across the French capital already know: An affordable and decent home - even one with 19th-century fixtures (no shower and a toilet on the ground floor) - is becoming nearly impossible to find in Paris.
The problem is concentrated in the city's far northeast neighborhoods, in parts of the 18th, 19th, and 20th arrondissements that have been havens for poor working families, especially the Africans and North Africans that are not often welcome elsewhere.
But in recent years the desirability of central Paris as a place to live and work has opened all 20 of the city's arrondissements to intensified pressures. Laws easing rent controls have encouraged new construction and renovation, and the scarcity of land and buildings in the central arrondissements has pushed speculators to neighborhoods formerly ignored.
``We're betting on the 19th!'' reads the glossy brochure of a development company that is building apartments in areas that hadn't seen privately funded projects for decades.
Although Paris is already an international city, the pressures are expected to build further as Europe approaches the 1992 single market and international companies seek office space - and convenient living quarters - in select European cities.
Earlier this year, French President Fran,cois Mitterrand deplored publicly that Paris office and housing prices ``are catching up with Tokyo,'' something of an exaggeration perhaps, but a reflection of how the steep price climb is perceived.
Housing rents in the Paris region have more than doubled over the past decade, according to the National Institute of Economic Statistics and Studies (INSEE), with the greatest jumps concentrated in the past few years. For the city of Paris, the increases are even more acute.
The result is that Parisians on the lowest economic rungs are being pushed out to the city's working-class suburbs, often to faceless and hostile public-housing projects that are the antithesis of the neighborhoods they've known.
``Neighborhoods are being renovated, which you can't deny some of them needed, but the problem is that people are being chased out in the name of this progress,'' says Marie-Claire Lourd, who runs a Roman Catholic service that guarantees the leases of working families seeking housing.
``The suburbs often place unbearable hardships on these families,'' she adds. ``They no longer have the familiar community that helps them get by, and the little jobs, as a maid or whatever got them to the end of the month, just don't exist.''
The city promises to build 20,000 low- and moderate-income housing units during the next five years, although Mayor Jacques Chirac admits land for these projects will be hard to come by, and very expensive. It will also spend $300 million over the same period for renovations.
``We're in a transition period right now, when few of our projects are complete and housing is admittedly very hard to come by,'' says Fran,cois Boulanger, assistant mayor in the 18th arrondissement. ``Some families may have to leave for the suburbs, but Paris will regain whatever part of its soul it lost. We refuse to become a city of offices and the rich.''
In the Goutte d'Or - immortalized by Emile Zola in ``L'Assommoir,'' his 19th-century novel of the French working class - architect and neighborhood activist Foraone Bogazzi says he fears the city's renovation will ``turn a lively neighborhood into something sterile.''
One INSEE study found 34 ethnic backgrounds in the neighborhood, Mr. Bogazzi says. But he adds that the renovation plan anticipates that 80 percent of the new and renovated apartments will be inhabited by people from outside the neighborhood. And that, he says, is not a good sign.
``Paris is slowly dying, because it is losing the variety of people and the little traditional arts and workshops that gave it life,'' says Patrick Angenault, a Paris businessman who acts as spokesman and defender of the Sacr`e Coeur campers. He became personally aware of the housing plight when shifting earth forced families from a building he co-owns in Montmartre.
Mr. Angenault says he won't dismantle the campers' tent until each one of the families has an apartment key in hand. But he says he has another motivation for his protest.
``This may sound corny, but it's these working-class neighborhoods that gave us Edith Piaf, Maurice Chevalier, and so much more richness and talent,'' he says. ``What will we be losing if we let them die?''