ON July 12, someone slipped a letter under Ann Shannon's front door and under the front door of every other apartment in Knickerbocker Plaza, a hulking government-subsidized complex on Second Avenue at East 91st Street.
When Ms. Shannon, 82, picked up her copy from the rose-colored carpeting in her entryway that Thursday, she did not understand the legal language. But she nevertheless got the message: Change was coming to the place where she had lived for 32 years.
The letter announced that the owner of the 578-apartment complex was withdrawing from the state's Mitchell-Lama program, which subsidizes lower- and middle-income housing, and would be raising rents to market levels by next summer.
'I told myself, I have a year to think about it,' Ms. Shannon said with a sheepish smile.
Transformation of housing for middle-income families into luxury apartments has become an ever more persistent refrain in the city, accompanied by ever more anger and unhappiness on the part of residents.
When Stuyvesant Town and Peter Cooper Village along the East River were sold in a record-setting deal late last year, howls of dismay were heard, not only from tenants but from champions of affordable housing. The intensity of their reaction was due in part to the immense complexes' symbolic role as havens for generations of working- and middle-class New Yorkers.
When the 5,881-unit Starrett City, on Jamaica Bay in Brooklyn, the nation's largest federally subsidized housing complex, was put on the auction block last year, similar protests erupted; there, no sale has yet been completed.
The same drama is playing out on a smaller scale at Knickerbocker Plaza, where residents are scrambling to pool their money to hire a lawyer in hopes of working out an arrangement under which their rents would not rise beyond a certain point.
Longtime tenants of the two rust-colored high-rises that make up the development watched uneasily as other Mitchell-Lama buildings around the city left the program in recent years. In the late 1990s, two neighboring complexes, Ruppert Towers and Yorkville Towers, exited the Mitchell-Lama program and went co-op. The three complexes make up the three-block-long development, which is bounded by East 90th and 93rd Streets and Second and Third Avenues, and is owned by the DeMatteis Organization.
The anxiety that filled the apartments and hallways of Knickerbocker Plaza after the letter arrived was especially noticeable at the complex's senior center, a popular meeting place for the elderly men and women who make up about a third of the buildings' 1,500 residents.
'Everyone is very stressed,' said Carol McCabe, a tenant of 32 years who helps run the center. 'You're afraid. You don't know what's going to happen to your life in a year.'
Residents are already eyeing the future uneasily.
'Where am I going to go?' asked Shirley Deonarine, a retired nurse who has also lived at Knickerbocker since it opened. 'Everywhere you turn, it's luxury rentals.'
Near Ms. Deonarine sat a retired Teamster who used to work for Pepsi-Cola, a former hospital administrator, a man who used to sell produce, two former employees of the city's Parks Department and a retired teacher. The group was typical of the people the Mitchell-Lama program was designed to benefit.
IN 1975, when the first tenants moved into Knickerbocker Plaza, which was built on the site of the former Jacob Ruppert Brewery, Yorkville was a much sketchier area, and far from the respectable address it would become.
'This was the wild West,' recalled Rita Popper, president of the buildings' tenants association. 'There were tenements and bars, lots and lots of bars.'
Paradoxically, it was residents of Mitchell-Lama buildings like Knickerbocker Plaza that helped make the neighborhood more affluent.
'The residents moved into that neighborhood when it was dicey and made it into a community,' said City Councilwoman Jessica Lappin, whose district includes the complex. 'It doesn't seem right that they don't get to stay.'
The owners, in turn, 'are determined to do everything in their power to soften the blow,' said Gerald McKelvey, a company spokesman. He said tenants on public assistance would be eligible for vouchers, under which their rent would be no more than 30 percent of their income. As apartments are vacated, they would be converted to market rate.
Even so, residents are fearful. 'Landlords have very deep pockets for legal advice and the tenants don't,' Ms. Popper said. 'That's what it comes down to.'
Meanwhile, tenants are left to contemplate the future or, in the case of Ann Shannon, the past.
Peering out the front window of her one-bedroom apartment, over the red-brick pedestrian walkway that passes through the complex on East 91st Street, Ms. Shannon can see the stone turrets of Our Lady of Good Counsel Church on East 90th Street over the tops of the maple and honey locust trees. Ms. Shannon was married in the church, her five children were christened there, and it is in that church that funeral services were held for her husband and both her parents.
Closing her eyes, as if feigning eternal sleep, she said, 'I thought they'd take me out of here with my arms crossed.'