Since its creation in 2007, the local activist group Rio de Paz, a loose coalition of youths and church members, has focused on one city's most notorious problem: the thousands of murders tallied in Rio de Janeiro each year.

But when President Dilma Rousseff, who took office in January, began to sack members of her cabinet amid corruption allegations, and the media followed up with aggressive investigations of misconduct at the highest levels, the civil society group began to take up another cause.

"We think that corruption is what kills," says Antônio Carlos Costa, a pastor and executive director of Rio de Paz.

They took to the streets to protest graft, carrying brooms to support the faxina, or sweeping up, and joining 20,000 protesters who showed up in Brazil's capital, Brasília, in September in the largest of more than 30 anticorruption marches held this fall throughout the country.

Mr. Costa says the small movement is growing as nonprofits and citizens seek to hold corruptive forces accountable.

Many countries in Latin America, such as Brazil and Mexico, are touting strong economies that make them important players on the international stage. But corruption, especially at the state and municipal levels, threatens to undermine their credibility in fighting crime.

Brazil's government is paying attention. Since President Rousseff has taken office, six ministers have resigned amid allegations of corruption, helping to boost her approval rating. Brazil also passed a freedom of information law this fall after years of debate, and formally launched, with the United States, the Open Government Partnership (OGP), a multicountry body that aims for transparency and the empowerment of citizens.

Latin America's corruption problems go back 500 years to the colonial era and persist today because of cultural acceptance, inequality – for example, low-paid police officers in Mexico often extract bribes to make ends meet – and the influx of drug money that can corrupt entire institutions.

Efforts toward greater accountability for wrongdoing run the gamut in Latin America. But most of the countries in the region sit somewhere in the middle, and they are pushing forward to help reverse the status quo – with Brazil paving the way, experts say.

"Brazilian society is passing through a new stage of democratic advances," says Fabiano Angelico, a São Paulo-based independent consultant on transparency.

Caught off guard?

The resignations in Rousseff's cabinet have helped spur an incipient movement. The latest to resign was Labor Minister Carlos Lupi, accused of taking money from nonprofits in return for ministry funding. He denied the charges but stepped down this month – preceded by the ministers of sports, tourism, agriculture, and transportation, as well as Rousseff's chief of staff.

Their resignations have been wildly popular among Brazilians, who see Rousseff as taking a stand where her well-loved predecessor, former President Luiz Inácio Lula da Silva, whose administration was dogged by a vote-buying scandal, did not. A September CNI/Ibope poll showed 85 percent of respondents calling her performance great, good, or normal.

Not all believe that the resignations represent a commitment to rooting out corruption, but rather Rousseff was caught off guard and is steering the narrative.

"She is tackling [corruption]," says João Augusto de Castro Neves, a Brazilian independent political analyst. "But if it were intentional it wouldn't be as disruptive as it has been.… She would have begun this administration with a clear goal of tackling corruption."

And Brazil's freedom of information law, while hailed by supporters, took years to pass. Mr. Angelico says the country may have been forced to pass it now to play down contradictions: It touts transparency with the OGP while lacking such principles at home.

Still, the resignations, the new law, and other new legislation that require budget transparency and forbid officials convicted of crimes from taking office have helped strengthen perceptions that corruption's grip is weakening in Brazil. Further, its ranking on Transparency International's annual Corruption Perceptions Index improved this year.

Unmaking 'systems of corruption'

Corruption continues to be a serious problem throughout the region, but countries are making important strides, says Alejandro Salas, regional director for the Americas at Transparency International.

Arthur Massuda, who works for rights group Article 19, which pushed for Brazil's freedom of information law, says that many of the gains at the federal level have not been embraced by states or municipalities – and that puts activists, and thus the movement, at risk. "Without a strong civil society, there can be no real fight against corruption," he says.

There are vulnerabilities ahead, including the stubborn inequality in the region and the growing clout of drug-trafficking money. And Mr. Salas says that countries such as Mexico and Brazil have to reconcile the fact they have modern economies and strong laws but continue "ancient practices" of patronage at the local level. "Generations in Latin America were born into systems of corruption," he says.

And Claudio Weber Abramo, executive director of Transparency Brazil, says that the movement could be undermined by murky goals. "It's a protest against something which they don't quite know what it is," he says. "Most people think this is a moral question. But it's not moral – it's very objective."