Unknown by many yet operating in huge numbers, the Center City Residents Association, a polite but pushy mob of Philadelphia watchdogs, gadflies and chlorophyll pushers has been hard at work in Center City for 60 years.

Sixty years - before NATO, before 45 rpm records, before Bill O'Reilly was born.

Tonight, they mark the milestone.

Formed by a couple of aproned, Peter Pan-collared women who would have been confounded by the title "full-time homemakers," the CCRA's first mission was to save Rittenhouse Square.

"Parking lot operators wanted to dig it out, make underground parking, and divide the square by running 19th Street straight through it," recalls 81-year-old Lenora Berson. Her mother, Sadie Ersner, one of the group's founders, took her to the organizational meetings.

Deceptively small then, CCRA delivered a Popeye-bicep punch powered by lawyers, businessmen and the politically connected who lived in the neighborhood that would one day become the economic and social lodestar of the city.

In time, it would spread its influence and draw its 2,200 members from the banks of the Schuylkill to Broad Street, JFK Boulevard to South Street.

Tonight, the Pyramid Club will sponsor a party for the group to celebrate its full docket's worth of subsequent victories, advocating for judicious development, victims' rights, clean sidewalks and more trees.

The fete is expected to draw hundreds who have benefited, directly or indirectly, from CCRA efforts - and city officials who will exchange hearty handshakes and good-will kisses. This isn't the kind of group you want to cross.

State Sen. Vincent J. Fumo said the CCRA had long made its voice heard, forcefully and effectively.

"The best neighborhoods are not determined by socioeconomic status but by the activities of the residents," he said, and CCRA fulfills that role. "We work with them on zoning, liquor licenses. I've had sidewalks repaired."

Vivian Seltzer, the group's president, said it pushes the city to serve the community. "Residential permit parking? Due to us. Cables underground? Due to us."

With modest dues - $35 a year - the group maintains 71 urban gardens, splits the cost with members for trees they plant, pays the Center City District $30,000 for extra street cleaning, and makes sure gingko berry sploosh is removed from the sidewalk before you can track it across the threshold. Once, it dispatched its minions to court to advocate for stiff sentences for quality-of-life crimes.

The group's meetings, open to the public, address the micro (will a roof deck spoil a neighbor's view of the skyline?) to the macro (crime).

It has helped save historic buildings, get public schools built in neighborhoods integrated both racially and economically, and it gives house tours of mansions.

Given Center City's image as the home of the city's elite, the role of a community advocacy group may seem like overkill.

CCRA's leaders say that although Center City has always been relatively well-off, at the end of World War II, it was not as upper-crusty as it had been. And even though people like Edmund Bacon, Ada Lewis, and Esther and Philip Klein lived nearby, voices that demanded respect from City Hall, there is always more power in numbers.

Today, members include students, artists, secretaries, nurses, teachers and social workers along with the monied and powerful. Rather than dilute the group's influence, the mix strengthens its muscle, said Seltzer, a psychology professor in the School of Social Policy and Practice at the University of Pennsylvania.

Of course, having connections - and people who can afford to give the organization major donations - doesn't hurt.

In the absence of a vigilant zoning and planning board, Seltzer says, the CCRA raised $100,000 two years ago to commission its own detailed planning study with recommendations on safety, lighting, parking, and commercial and residential development.

The group's most recent sortie has been to shoot warning flares at the Irish developer Castleway Properties, which paid $37 million for a former Parking Authority site in Rittenhouse Square. Tentative plans call for a skyscraper that could be one of the city's tallest residential buildings, a hotel, shops and underground parking.

"We have been spending a lot of time with them," Seltzer said. "Our purpose is to assure that our way of life in our neighborhood is protected."

Which is not to say they're elitists.

In March 2004, at a City Council hearing, a CCRA representative was the only citizen to protest a proposed tax break worth $21.5 million for a major insurance company. She argued that the proposal "undermines the integrity" of the city's tax structure by giving tax relief to a few. (The measure passed anyway.)

Although members do, often, find themselves raising objections, it would be wrong, they say, to cast them as obstructionists. They have been attacked at times for not fighting hard enough to preserve historic structures.

The group understands the need for growth, Seltzer said, but it has assigned itself the task of seeing that it's guided more by wisdom than greed.

The mission, the board of directors believes, is to make sure that Center City remains a neighborhood, and not, they say, just a place where people live.