A casual passer-by on Eighth Avenue in Chelsea could easily pass a particular cluster of high-rises on the west side of the street and think they're just a group of typical Manhattan residential buildings.

But they're not. Mutual Redevelopment Houses Inc. - better known as Penn South - is more like a town within the city. Penn South has a uniformed security force, a staff of 110 employees, its own power plant (which enabled the development to have uninterrupted power during last year's blackout), a community garden, an exercise room, an extremely active seniors' program, a group of stores and restaurants on the premises, and even a theater or two.

Penn South was built as part of a wave of city- and state-subsidized co-op developments in the "˜60s, along with Starrett City, Co-op City, Rochdale Village and quite a few others. But it hasn't had the difficulties of, for instance, Co-op City, which had to close most of its garages because of structural problems. Penn South still remains an extremely desirable place to live for people looking for affordable housing - at one time the waiting list, which has been supplanted by an apartment lottery, was 15 years long.

And perhaps most remarkably, Penn South's shareholders have consistently voted against "going private," although if they gave themselves the right to sell their apartments on the open market, they certainly would be able to get very high prices for them. Instead, they've decided to give others the same opportunity for affordable middle-income housing that they had. By contrast, several other subsidized co-op developments did vote to go private, such as the Grand Street co-ops - which were built around the same time and designed by the same architect.

Penn South's decision shouldn't be surprising, because it is known for its political liberalism - one gets the feeling that the complex is a mini-Blue State unto itself. Many of the early residents were members of the ILGWU (International Ladies' Garment Workers' Union, the complex's original sponsor) and other unions. On the dais at the complex's opening ceremonies in 1962 were President John F. Kennedy, Eleanor Roosevelt and David Dubinsky, head of the ILGWU. As a matter of fact, Penn South (meaning "south of Penn Station") was known at first as the ILGWU Houses.

Penn South was originally a slum clearance project, says Brendan Keany, the development's general manager. (Residents of the tenements that were torn down to make room for it did, by the way, get first crack at the apartments). In those days, Chelsea was dominated by tenements and factories, with pockets of drug dealing and prostitution.

Even some people who lived in Penn South during the "˜60s and "˜70s remember the surrounding area as having few restaurants, few supermarkets and poor street lighting. Now, of course, "Chelsea has become an upscale neighborhood, and the old brownstones nearby have greatly increased in value," says Walter Mankoff, Penn South's treasurer and a resident since 1971.

The development was built as a city-sponsored Article 5 Redevelopment Corporation under a program similar to, but slightly different from the better-known Mitchell-Lama program. The cooperators came from not only Manhattan, but from Brooklyn, the Bronx and Queens, and most came to the development from rental apartments. Originally, says Nat Yalowitz, a former co-op vice president for 15 years, "You had a totally non-resident board. About three years after it was occupied, we elected our first resident board member. Within five years, you had a board made up of residents," and people began to feel more of a stake in their community and to get more involved.

"Many of the original people who moved in were people who were close to retirement age, and the development is still about 70 percent over 70 years of age," says Keany. Thus, it qualifies as a Naturally Occurring Retirement Community, or NORC (more about this later). Still, the number of younger people is increasing, as is evidenced by such entities as the Parents Committee and the Toddler Playroom Committee.

Penn South stretches from West 23rd to West 29th Streets, between Eighth and Ninth Avenues. It contains 15 buildings with 2,820 apartments, surrounded by lawns and trees, with two playgrounds. Occupying commercial space here are a Dallas Bar-B-Q, a Clearview movie theater, a tennis court, a medical clinic, a Gristede's supermarket, a Dunkin' Donuts and, most recently, the trendy Upright Citizens Brigade comedy theater, among others.

Monthly maintenance charges, Keany says, are "very reasonable," about $150 per room. David Smith, a longtime, influential cooperator who served as board president for 20 years, says, "A two-bedroom apartment here sells for about $18,000, as opposed to one in the Grand Street co-op, which sells for over $599,000." Subsequently, a two bedroom in Penn South goes for about $23,000, and a three-bedroom, $29,000, compared to those same downtown apartments that range from about $400,000 to upwards of $750,000.

Both equity and maintenance charges have gone up, of course - Keany says maintenance charges will probably go up in a year or so - but slowly and in relatively small amounts.

Because the co-op is now more than 40 years old, there have by necessity been some major capital improvement projects. In the mid-1990s, for example, the buildings' windows were all replaced. This project, says Mankoff, cost about $11 million. More recently, about a year ago, Penn South's underground electrical cables, which also had deteriorated, were replaced, a project that Keany said cost about $5 million.

And just during the past few months, the buildings' front doors were replaced by push-button doors. Now, when a resident comes in from the outside, he or she can turn a key on the wall of the entranceway and both doors swing open automatically. This both helps elderly shareholders, who need time and room to move their walkers or wheelchairs, and shoppers who may be carrying heavy bags and don't have a free hand to open the door.

Penn South's most unusual physical feature, many people would agree, is its cogeneration plant, a low-rise building between West 25th and 26th Streets. The building housed an old-fashioned steam boiler plant until about 1986, when the co-op decided to convert it to a cogeneration facility.

Nowadays, it generates the buildings' electricity, provides hot water, and provides heating and cooling through a convector system (although some cooperators have their own window air conditioners to supplement the convectors). All in all, says Keany, it saves about a half-million dollars a year.

These projects, and others, says Mankoff, are all financed by a combination of "borrowing and equity assessments." And, adds Mankoff, Penn South also took advantage of low interest rates to refinance. "We recently refinanced our mortgage through a partnership between Fannie Mae and the Amalgamated Bank for $63 million at 4.17 percent."

Penn South is known for its active community life - Keany estimates that at least half of all residents vote at the annual shareholders' meeting. Penn South has not only a board of directors but a Co-op Council, which takes care of problems within the buildings themselves, such as lighting in the stairwells.

The co-op also sponsors many groups and clubs, which are coordinated by the education director, Naomi Goldstein. Some of these include a woodworking club, a recently introduced ceramics studio, the aforementioned toddler playroom and youth recreation room, a computer club, and more.

An exercise room with state-of-the-art equipment, including treadmills, cross-country skiing machines, weightlifting machines, exercise bikes and a rowing machine was established several years ago. With 500 members now, the initial outlay to build the facility has been recouped through membership fees.

On the south side of 25th Street is the Jeff Dullea Intergenerational Garden, where cooperators of all ages have individual plots to grow flowers and vegetables (this writer has grown tomatoes, basil, sunflowers, mint, lettuce and carrots), and where a cherry tree, a fig tree and a grapevine grace the common areas. The late Mr. Dullea was a horticulturist who originally came from the Midwest. A former co-op president, he wanted to give kids who grew up in the city - as well as adults who missed gardening - the same opportunity to enjoy this outdoor activity that he had been given.

"We're probably unique," says Goldstein. "We make an effort to provide all kind of services "¦ we see ourselves as a community with a interest in improving our quality of life."

Penn South also sponsors a credit union that offers low-interest loans. According to Goldstein, "Many cooperators financed their equity payments with loans from the credit unions." At one time, the co-op sponsored its own supermarket as well, but it has been replaced by several chain supermarkets, most recently Gristede's.

Separate from these co-op sponsored activities, yet closely related, is the organization known as Penn South Program for Seniors. The program, Smith recalls, was the first senior center established under the NORC program in 1986. It had become clear that the co-op's population was aging and the seniors' needs presented a new set of challenges. Today, the organization has a staff of social workers and other professionals and sponsors a wide array of activities. Offerings listed in the October 2004 newsletter include a poetry workshop, a watercolor/still-life painting workshop, a chair exercise session, a lecture on opera, tai chi, yoga and a choral sing-along.

All in all, says Mankoff, the program gets about $280,000 in government funding each year for senior support services, "and the co-op also puts in a sizeable chunk of aid."

One important service of the program is to help seniors stay active and get back on their feet again after an illness or a personal setback. One example concerns a recent widow, who had become frail and had few relatives to care for her. She began withdrawing socially, and over the course of several weeks, her apartment was not cleaned and her clothes went unwashed. A neighbor referred her to Penn South Seniors, where a social worker from the group hired an aide, who helped the woman with the housecleaning and cooking that she was no longer able to manage on her own. The organization also provided a walker and a wheelchair to get the woman out of the house, thus encouraging her to start going again to meeting of the groups that she once belonged to. In a short time, the woman was back interacting with friends and neighbors and part of the community once again.