After more than six decades of stifling dissent—sometimes by force—the party is also using Shenzhen to test ways of strengthening public oversight of local government to root out corruption that the party itself admits has become the greatest threat to its grip on power.

It is a far cry from Western-style multiparty democracy, but this experiment—branded "small government, big society"—is seen by some leaders as a way to forge a new political model that maintains authoritarian rule while responding to the needs of an increasingly complex society.

At the forefront of the experiment is Sunny Lee, who runs a nongovernmental organization in Shenzhen that teaches the children of migrant laborers. His Ciwei Philanthropy Institute, which he founded in 2007, caters to children left alone when their parents work overtime at a nearby nuclear plant and in a factory making garments for Polo Ralph Lauren Corp.

After two years trying in vain to get the patronage of local officials, he was suddenly invited by the government to submit a report on his organization last year, and then to register legally this year, and to apply for state funding.

"Before, the government wanted to do everything itself. It thought it could solve every issue," said Mr. Lee, who isn't a Communist Party member. "Now I think it realizes that it needs help from society."

The experiment lies at the heart of a debate that burst into the open when Chinese Premier Wen Jiabao made a surprise call for political reform during a speech in Shenzhen in August, marking the 30th anniversary of free-market reforms launched there.

Since that speech, many inside and outside China have been asking what motivated Mr. Wen—who is due to retire with other top leaders in 2012—to make such a bold public appeal.

His speech raised more questions than answers for those in China looking for signs of political change in what has been seen as a hard-line administration. Was he seriously reviving calls for democratic reform that were crushed by the army around Tiananmen Square in 1989? Is he paying lip service to the idea in the twilight of his career? Or is he promoting limited internal reforms designed to strengthen one-party rule?

Does he have the support of Hu Jintao, China's president and Communist Party chief, or of Xi Jinping—Mr. Hu's presumed heir—and other members of the next generation of leaders?

These questions have grown more pressing since Liu Xiaobo, a jailed Chinese dissident, won the Nobel Peace Prize this month, and a group of Communist Party elders published an open letter last week calling for media freedom.

More than 100 Chinese political activists also issued a statement online Friday calling on the government to release Mr. Liu and introduce democratic reforms.

The secretive four-day meeting of the 371-member Central Committee, which finishes Monday, is expected to discuss political and economic reforms, as well as personnel changes ahead of the 2012 leadership change.

One of the key questions is whether Mr. Xi will be promoted to the powerful Central Military Commission, thus confirming his status as heir apparent.

Shenzhen may offer clues on how the debate on political reform is playing out behind closed doors at the party meeting. The city is one of the country's most populous and progressive, with a population of 14 million—about 10 million of whom are migrants.

It was here that Deng Xiaoping, China's former paramount leader, established the country's first Special Economic Zone, offering tax breaks and other perks to foreign investors, in 1980.

It was also here that he revived the economic program, which had been stalled by party conservatives after the 1989 Tiananmen crackdown, when he visited on a "southern tour" in 1992.

And it is here that local authorities, anxious to preserve Shenzhen's pioneering role, have been trying to develop a smarter, leaner form of authoritarian rule.

Since 2004, the city has slashed a third of its departments, transferring and retiring hundreds of officials, and forcing others to give up their parallel positions on business associations, charities and other civic organizations.

Since last year, it has eased legal restrictions on those civic organizations, allowing them to register without direct supervision by a party or government official, to seek private funding in China and overseas, and even to hire foreigners.

In addition, the city has started to buy services from these organizations on a contractual basis, to help address social problems such as the mental health of migrant laborers—an issue highlighted by a spate of suicides at a factory in Shenzhen earlier this year.

As a result, Shenzhen now has more than 3,500 nongovernmental organizations, more than double the national average per capita, according to Wang Lizong, secretary general of the Shenzhen Social Organizations Federation.

Local authorities also scrapped "jobs for life" for new government employees this year and began phasing out cradle-to-grave welfare for existing officials. Next on their list is a plan to transform neighborhood committees, the lowest unit of party organization, into more independent bodies.

"Now they should play a supervising role over governments and let the government know local residents feel unsatisfied and why," Liu Runhua, head of Shenzhen's Civil Affairs Bureau, was quoted as saying by the official Xinhua news agency.

An even bolder idea, put forward in 2008 but apparently on hold—is to strengthen media supervision of government, and establish a more independent anticorruption agency.

Some of these changes have been introduced unofficially in other cities, but Shenzhen is the first to try to establish a legal framework, according to local officials and academics.

The city is also unique in having the explicit support both of Mr. Wen—who has visited eight times since becoming premier—and of Wang Yang, the party chief of Guangdong province, which surrounds Shenzhen. Mr. Wang, 55, is a member of the party's 25-member Politburo and a leading candidate for promotion to its Standing Committee, the highest decision-making body, in 2012.

The Shenzhen reforms have met resistance within the party, say local officials and academics. Some oppose them because they stand to lose power or perks. Others have ideological objections, fearing that social organizations could challenge party rule.

"For government, giving up power is a painful process," said Tan Gang, deputy head of the Communist Party School, the party's main think tank and training institution, in Shenzhen. "It is a selfish creature."