The fluorescent green T-shirts and orange hats seem to be everywhere in Rocinha, one of Latin America's largest slums--on its snaking asphalt road, in its shaded, sloping alleys, in its muddy, fetid nooks.

The people wearing the shirts and hats are community workers who spend their days sweeping, lugging and dumping trash from a place where garbage used to clog the streets.

The swish, swish, swish of their brooms has become a prosaic but potent symbol of the powerful changes wrought since the early 1990s in Rio de Janeiro's favelas, the vast shantytowns that blanket the hillsides of this city of 6.5 million.

Favelas such as Rocinha, home to between 150,000 and 200,000 people, were once known not just for unsanitary conditions, but for nightly violence, overwhelming unemployment and paralyzing poverty. For decades, the government of Latin America's most populous nation mostly ignored those conditions--and those communities.

Now that is changing. A combination of community activism and government initiative has slowly transformed some favelas into vital neighborhoods that now boast public services, sports complexes, newspapers and thousands of new businesses.

Rocinha now has more than 2,000 shops and services. It has five banks and lending institutions, three newspapers and two supermarkets. It has a Web site (http://rocinha.com.br). And, next month, Rocinha will receive another stamp of legitimacy--its first McDonald's.

"In the last few years, so many things have come to Rocinha that people don't have to go out of the community" for services, said Marli Felix de Souza, 34, who has lived there most of her life and now runs a government-funded jobs program. "It's been the government, the people, the businesses, together. Separately, they wouldn't make it."

The revolution in Rio's favelas is far from complete--12 people were slain in one favela in a single night this month--but the recent changes signal a sea change in how Brazil battles one of its most urgent and insidious problems--urban poverty.

More broadly, officials with the Inter-American Development Bank, which has lent $180 million to the government's $300-million favela development project, suggest that what has happened in Brazil represents a remarkable shift in the way many developing countries are grappling with poverty.

"In the past, the idea was to move [the poor] because they're 'in the way,' " said Christian Gomez, the bank's division chief for social programs in South America's Southern Cone. "Now the idea is that you directly involve the people to improve their livelihood, infrastructure, how they organize themselves, how they go to work. There's constant involvement of the community in all aspects of the program."

Community involvement came easily for residents of Rocinha, which lies snug between two of Rio de Janeiro's most affluent communities. It has long boasted of its activism and cohesion, made easier because most of its residents came to Rio from the same area of Brazil, the Northeast.

Like most poor communities in Rio, Rocinha rarely saw politicians, who tended to come around just before elections only to vanish again after the vote. Meanwhile, schools went unbuilt, roads unrepaired. Poverty blossomed along with the trash in the streets and alleys.

Yet the longer government ignored their community, the more active they became. They fashioned their own water and electricity systems. They built their own schools.

Seething over the lack of day care in the favela, for example, the Women's Association of Rocinha opened a nursery school eight years ago. It was immediately filled to capacity. Today, the 100 children, aged 2 to 4, who scramble and squeal around the building in second-hand clothing and Tweety Bird backpacks receive not only basic schooling but three square meals and a shower--amenities unavailable to many at home.

"This is like a second home," said Elaine Ramos Vieira, 26, a lifelong resident of Rocinha and vice president of the women's association. "They eat breakfast, lunch and dinner here. They learn here, they sleep here, they play here, they shower here, they do everything here."

The association no longer needs to hustle for money to support the school, because the government took it over four years ago. Now the school plans to expand so it can tend to more children and offer more activities.

Such partnerships between private groups and the government are becoming common in favelas. Three years ago, the government gave the women's association money for a garbage truck, along with funds to hire 80 trash collectors, now ubiquitous in their T-shirts and caps. It has built concrete supports to keep homes that are no more than shacks from tumbling down the hillside during Rio's notorious summer rains. Last year, it shored up the community's fraying main road, and it has opened an office designed to put unemployed skilled laborers in contact with employers.

The moves have earned reluctant praise from residents. "They did structural work, and they started some new projects, but investment in education is still low," said Marcos Gentil, 31, a resident of Rocinha who now works for Balcao Sebrae, a nongovernmental organization based there. "They could do much more."

Antipathy toward the government runs deep in most favelas. Brazilian governments historically have treated inhabitants of the hillside slums as squatters and denied them such services as electricity and running water. Even as works such as the film "Black Orpheus" romanticized favela life for worldwide audiences, residents in the crowded, filthy, poverty-addled communities saw their existence grow ever more desperate.

Wrongheaded economic policies in Brazil drove up the number of those living in poverty, which drove up the number of favelas and their populations during the 1970s and '80s. Drug use brought unprecedented violence. Police terrorized residents. Every year, thousands of slum dwellers died when their shanty homes slipped down the hillsides in summer storms. And unemployment, always high, spiraled upward.

Even today, Rocinha's people are by no means at rest. Signs of their continuing struggles abound. On a recent afternoon, three policemen, taut and grim in their gray uniforms and black boots, bounded up a side street, guns drawn.

"Something must be hot," whispered a woman in a car.

A few people glanced up at the policemen. Others stopped to let them pass. But as the officers climbed the hill, along came a line of men in fluorescent green T-shirts--weary, sweating, mud-splashed garbage collectors bent under bulging bags of trash who seemed barely to notice the commotion.