Philadelphia -- Like San Francisco, Philadelphia has a Market Street leading to City Hall with wide traffic lanes, brick sidewalks and a robust business district - - in fact, when surveyor Jasper O'Farrell designed San Francisco's main drag in 1847, he patterned it after Philly's. Both streets have lots of shopping, and they draw crowds of strollers and tourists.

But there's one big difference that O'Farrell probably never counted on.

In San Francisco, those strollers and tourists step over, around and alongside thousands of homeless people panhandling, shooting dope, pushing shopping carts or sleeping on the cement. In Philadelphia, you have to look long and hard to find a single panhandler, or homeless person of any kind, anywhere along Market Street.

Or in its downtown, for that matter. Or in its famous Independence National Historical Park, where the Liberty Bell sits among other icons of the foundations of American history.

That's because the City of Brotherly Love, perhaps more than any other in the United States, has solved its problem with chronic homelessness. In stark contrast, that other city known for love -- the Summer of Love -- has the most visible crisis of chronic homelessness in the nation.

"A few years ago, it didn't look anything like this," said Josette Adams, 36, as she pushed her toddler son in a stroller along Philadelphia's Market Street.

"You'd be walking like this, and people were sleeping everywhere, doing their business in the street, panhandling, yelling at you, getting in your face." She paused under the balmy sun, smiling slightly as she looked at the slowly moving mass of tourists and shoppers all around.

"Now?" she said. "I can come down, get a nice lunch, walk around with my son. You can have a nice day."

The secret to this success is not that the homeless were carted off to other cities in police vans. Or thrown in jail. Or so denied welfare or housing that they had to leave town. They weren't.

Philadelphia simply figured out how to truly help its chronically homeless people -- how to give them more than just a blanket and a sandwich and an emergency cot. It got them into permanent housing with counseling services to help them handle their personal demons, particularly mental illness; it got them into drug rehabilitation; it got them into decent, clean shelters that are open 24 hours a day and have teams of doctors and social workers in offices a few feet away.

And, most important of all, the city sent squads of outreach workers into the streets, day and night, to persuade -- not force -- the homeless to make use of all these services. When the outreach workers made the offer, they had services and housing to offer right there on the spot, with no waiting. That hasn't been the case in most of San Francisco's programs -- and that's a crucial difference, because most homeless people don't or can't wait or keep schedules.

Slowly, but surely, Philadelphia reached a point that homelessness experts from San Francisco to the Eastern Seaboard long for -- "The Tipping Point," a term coined by author Malcolm Gladwell in his book of the same name. It's the moment at which all the hard, seemingly impossible work at the beginning takes on so much momentum that it turns a corner, takes on a power of its own and effects sweeping change.

How did this turnaround happen?

Most folks point to Sister Mary Scullion, a nun who owns no home and lives with homeless people she rescues from the sidewalk -- but who can pick up the phone and get a quick return call from everyone from the mayor on up to President Bush's homelessness czar.

She spent the past two decades walking every Philadelphia park, alleyway and street corner where the down-and-out held out their hands or hid in a haze of mental illness, and she asked them again and again if they wanted to come inside. She built or badgered local leaders to build hundreds of supportive- housing units and launched outreach teams to emulate her street skills -- and she did these things in such a famously relentless but caring way that she was called "Mother Teresa of the Homeless."

Today, the city's homeless programs director, Rob Hess, uses her techniques as his guideline and has spent several years expanding them. Along with Scullion's ever-forceful assistance, Hess has launched cutting-edge programs that team up police with outreach counselors; created "Safe Haven" housing where the drug-addicted and mentally troubled can move in before they are stabilized; and coordinated all city services through a central office so counselors can keep track of which homeless person needs what and how much.

Hess says there is much more work to be done. The modest Scullion, a member of the Sisters of Mercy Catholic order and someone who loathes being called a saint, agrees.

But the chronic homelessness crisis is now so tamed in this city that Scullion and other homeless advocates who used to fight City Hall have now turned the bulk of their attention to their next cause: creating more affordable housing to prevent the poor from tumbling into homelessness and refilling the street.

"To me it was just so simple," Scullion said, standing outside the headquarters of Project HOME, the homeless housing and counseling center she co-founded in 1989 with Joan Dawson-McConnon. "What enables a person to get off the street? They see that it's possible. All we did was make it possible."

The headquarters are in an economically ravaged stretch of North Philadelphia that contains both lawns trimmed with pride and crowds of young men on stoops downing 40-ounce beers. As she talked, everyone who passed -- street toughs, chronically homeless people in her housing program, elderly neighbors -- called out a hello or stopped to chat.

"Sister Mary, Sister Mary!" stuttered one mentally slow woman, a Project HOME resident. "I went to church, I went to church!"

Scullion is a lanky woman whose brown eyes have an uncanny ability to look unthreatening and sharply searching at the same time, and she focused them laserlike on the woman's face a moment before hugging her.

"That's a good idea," Scullion said, hands on the woman's shoulders, peering into her face again. "You're doing so well, getting out and around so well."

The woman grinned, eyes struggling to focus on the sidewalk before her, and she moved slowly past.

"We are all each other's mirrors," Scullion said. "How we see each other affects how we help each other. If you're on the street and people show you respect, you feel respect."

That philosophy started everything that changed the face of Philadelphia in 1997 when City Council President -- now Mayor -- John Street proposed a rigid anti-loitering law aimed at clearing the streets of panhandlers. In the mid-1990s, city officials estimated that 4,500 homeless people lived in the city, and half of those were on the street at any given time; the downtown was considered overrun and inhospitable to tourists.

By then, Scullion already had become a street hero because of her campaign in the mid-1980s to take mentally ill "shopping-bag ladies" off the sidewalks and house them, and because she founded Project HOME despite neighborhood opposition. She packed City Council hearings with supporters to plead for a more sensitive approach than pure police action -- and she won.

What resulted was a law making loitering a civil offense, not criminal, and mandating that police first call one of Scullion's outreach workers when they encountered a homeless person blocking the sidewalk. The city earmarked nearly $6 million for new services to help the down-and-out, giving the outreach teams more housing and counseling to offer on the spot.

The result? Street counselors responded within 20 minutes to every call. The homeless started moving into improved shelters and other housing that provided counseling services. And the streets started to clear.

By 1998, there were 850 chronically homeless people on the streets.

Today there are 130.

The Greater Philadelphia Tourism Marketing Corp. reported last month that since homelessness efforts began in 1997, overnight visits by tourists have jumped 40 percent -- while the same figure nationwide rose just 8.8 percent. Part of that is due to a big push by the city to promote tourism and the addition of two dozen hotels and more than 100 restaurants in the central city -- but the virtual elimination of panhandlers and shopping carts heaped with their belongings made a key difference.

"Ten years ago this was a sort of hellhole without any tourists," Dr. Marcella Maguire, director of the city's chronic homelessness initiatives, said of Center City, the main shopping and financial district, which sits apart from the historic district that houses Independence Hall. "We had abandoned buildings, few restaurants, people didn't want to come. Not attractive.

"Now -- it's night and day."

Today, the city puts 20 outreach workers on the street day and night, ranging from general social workers to police officers assigned to outreach and mental health specialists. And Hess, the city's homelessness "czar," makes a priority of pounding home the concept, day in and day out, that the homeless must be engaged and immediately brought into shelters or housing with counseling services upon demand.

"For anyone to say 'I can't help this guy on the street' is not acceptable, whether it's our cops or our outreach workers," said Hess, who is regularly tapped by homeless officials in cities across the country -- including San Francisco -- for advice. "I've waked the managing director (Philadelphia's city manager) up before to get him to open up a service so we can bring someone inside right away. You need the field guys to know that they are empowered to call us, me, anyone, at any time.

"You do this long enough, hard enough, and you get a paradigm shift," he said. "We're still a work in progress, but I think we reached that shift."

So does San Francisco Mayor Gavin Newsom, who dispatched a team of homeless advisers last winter to check out Philadelphia's system. They took particular note of the outreach system and incorporated the same philosophy into the 10-person Homeless Outreach Team begun in May to try to persuade chronically homeless people to move into shelters, housing or counseling programs.

"What Philadelphia tells me is that there is no excuse not to take care of this problem," Newsom said on a recent stroll through U.N. Plaza, past lines and groups of homeless people sleeping, carousing and furtively smoking crack beneath blankets. "It tells me that it is possible to make a difference and make an impact with incremental change -- and the pieces we are missing most are more outreach, centralizing our system and more supportive housing."

He stared at a cluster of shopping carts, and several homeless men recognized him, waving and shouting at him happily: "Hey, Mayor! Good to see you!" He smiled back and said quietly behind his hand, "We can solve this. I know we can."

To be sure, there are differences between Philadelphia and San Francisco.

Philadelphia has a population of 1.5 million, and San Francisco's is about 760,000. Philadelphia's total homeless count on the street and in shelters and temporary housing is about 6,000, while San Francisco's is anywhere from 8,600 to 15,000. Philadelphia has 130 chronically homeless people on its streets; San Francisco has 3,000.

Philly's subzero winters and hot, humid summers make it miserable, and even deadly, for street people at the height of both seasons. In San Francisco, people can sleep on the sidewalks year- round with no fear of freezing or heat exhaustion.

San Francisco spends $104 million each year directly on homelessness programs and another $96 million indirectly on hospital, jail and other costs. Philadelphia spends $60 million directly on homeless programs and doesn't have an estimate of its indirect costs -- but they would be less, proportionately, because the hard core typically use about 60 percent of any city's resources spent on homelessness, and Philly has so many fewer hard-core homeless.

As for its permanent supportive housing stock, meaning housing with counseling on site to help the hard core get over crippling substance abuse and mental troubles: San Francisco has about 2,900 units overall, and Philadelphia has 6,500.

San Francisco has 1,800 shelter beds for families and singles, while Philadelphia has 2,700. And more significantly, San Francisco has 10 -- soon to be 15 -- city outreach workers for its 3,000 hard core, while Philadelphia has 20 outreach workers for its hard core of 130.

"Philadelphia has done a great job -- probably the best in the country, for its size -- and what San Francisco could learn from this is three things, " said Dennis Culhane, a University of Pennsylvania professor who has conducted definitive studies of chronic homelessness in New York, Chicago and Philadelphia and other cities around the country over the past decade.

"You need to have one central, coordinated intake authority for placing chronically homeless people in housing, you need one coordinated, central street outreach program, and you need enough real housing to handle all the people you are taking off the street," he said. "And these programs have to be 'anti-creaming' -- taking the most difficult, chronically homeless, not just the easiest ones to get at."

Do these things, he said, and San Francisco could see significant changes within four or five years, which is about how long it took for Philadelphia and New York.

"People have to realize a problem like this doesn't go away in 12 months, and it won't go away at all unless you have a real commitment by the city and the public," Culhane said. "You have to keep your eye on the prize.

"It's not a bad idea to have a law against panhandling (like Philadelphia's, or the similar one enacted this spring in San Francisco), but unless you have programs to put people into immediately, the law is useless," he added. "It's all about the permanent housing. Just moving people around from jail to street has been proven not to work."

That credo is put into action every day by the civilian and police outreach teams who drive and walk Philadelphia's streets to gently persuade the hard core to go inside. Ask who puts in the most shoe-leather time, and most on the teams point to Sam Santiago.

He is a 42-year-old former cop who starts out every day before dawn with a list of open programs and a little black book that contains the names and conditions of more than 1,000 homeless people he's personally contacted in the past couple of years. One recent morning, Santiago patrolled most of downtown, the railroad tracks along Schuylkill River and the popular Logan Square circular park before he got his first nibble.

"Hey, what's with this New Keys (supportive housing) program I've been hearing about?" growled John Dilliplane, striding up with a Hefty bag of clothes in one hand and a scowl beneath his gray mustache. "Don't give me no crap about shelters, because I hate 'em."

Santiago stopped and regarded the 46-year-old man with a slight smile. "You serious?" he said. "I mean, don't pull my chain -- you serious?"

"Yeah, sure, I guess, maybe," said Dilliplane.

"New Keys is for people who've tried programs before, have plenty of problems, but are willing to give a bed another try," Santiago said. "You in?"

"Sure, but I gotta go there myself," Dilliplane said. "I don't like company."

"Fine," responded Santiago, writing on a business card. "Walk to this address right now, a few blocks away, and they'll talk to you right now. And you have any trouble, here's my phone number, and I'll be back out here tomorrow."

As Dilliplane walked away, Santiago shook his head. "This one might stick, " he said under his breath.

"Sometimes it will take months, or even years, before someone is ready to go inside after you've been talking to them day after day, but that's OK if that's what it takes," he said later. "You force them in too early and, boom, they'll be back on the streets before you know it.

"But you've got to make sure of one thing: If you offer them something, you'd better be able to deliver, right then and for real, or it doesn't mean s -- ," he added. "You can't B.S. these people. They can smell a con a mile away. "

At 47, Patty Baltimore had heard an earful of what she considered false promises and failed opportunities before she was finally ready to listen. She bounced from shelter to street to rehab to mental health services in the city until Maguire finally hooked her up with a full-time case worker this past year -- and now, after she'd all but given up on getting lasting help, Baltimore has her own apartment for the first time in seven years.

"You could illuminate this city and see my tears all over it," Baltimore said a few weeks ago as she moved into her east-side Philadelphia digs, a one- bedroom Victorian unit with white kitchen cabinets she had scrubbed so hard they sparkled. "The only thing that was missing was that I needed to learn how to trust." She teared up and pointed to Maguire and the other two social workers who helped her move in.

"Y'all are angels," she said. "It just took me awhile to see it."