The party congress, held every five years, starts next Monday in Beijing's Great Hall of the People. It offers President Hu Jintao and other leaders a chance to reshuffle membership on the party's Politburo Standing Committee, China's most powerful political body.
The event also gives Hu and Premier Wen Jiabao an opportunity to establish their credentials as corruption fighters and lay out their political agenda, which includes spreading prosperity more evenly throughout society.
In recent weeks, police have swept Beijing's streets of potential troublemakers and tightened their grip on cyberspace.
China's leaders "don't want any unharmonious incidents ahead of the congress," said Peking University law professor He Weifang, a proponent of political reform. The campaign has included:
•Roundups of aggrieved citizens. Police have increased patrols in the capital's southern Fengtai district, where a slum that draws rural Chinese who come to Beijing to plead for help from the central government. The city has threatened to demolish the area, known as Petitioners' Village.
"I don't know where I can move to," said Han Hongbu, 55, a farmer from eastern Shandong province who said he is in Beijing to protest the seizure of farmland by local officials he said are corrupt.
Han and other petitioners said some of those detained in recent days have been sent to psychiatric centers in the suburbs.
"There is a concerted effort to clean up the streets, which you can see from police statements" in the Chinese media, said Mark Allison, researcher for Amnesty International in Hong Kong. "What is extremely worrying is that there is unofficial detention of people that … violates Chinese law and international principles governing detention."
•Arrests of human rights activists and lawyers. Amnesty International said activists, including Li Heping, a prominent lawyer known for his defense of Christian activists, have been detained and tortured.
Li said last week that he was recently abducted and beaten by unidentified men who used electric batons on him.
An activists' network, Chinese Human Rights Defenders, said in a Sept. 21 report that the government is using secret detention facilities — "black jails" — to house protesters and others ahead of the party congress and next summer's Olympic Games in Beijing.
"The crackdown flies in the face of official promises to improve human rights in the run-up to the Olympics," Amnesty International said.
•Raids on Internet data centers and websites. Chinese authorities in August pulled the plug on several data centers housing computer servers that host thousands of websites.
The raids were an escalation of previous efforts to police the Internet by attacking or bringing down individual sites. "Some of our 4,000 servers were shut down for the first two weeks of September," said Tang Haobai, who works in the business department of Shanghai's Waigaoqiao Internet data center.
Tang said government officials are "checking for illegal information — mostly pornography, but some websites also had political content" on blogs, chat rooms and other online forums.
Tang said servers at his center are running again but that the message from authorities is clear. "We need to manage our clients more carefully," he said.
•A propaganda campaign. The Communist Party, plagued by corruption scandals, is trying to reclaim the high ground by promoting 53 "moral models" — squeaky-clean individuals who have made sacrifices for the country.
The party also is trying to clean up the state-controlled media, banning sexually daring ads for push-up bras and sex toys. The party says it is banning "vulgar" material and "sexually provocative sounds" from TV shows; and American Idol-style talent shows have been barred from prime time. This month, Hollywood movies are being pulled from movie theaters in favor of patriotic Chinese films.
The congress will cap a 70-day campaign announced by police to improve the "tranquility" to Beijing. Traffic safety is the major target, and potential dissidents are also being targeted.
"Traffic management is getting stricter and stricter ahead of the congress," taxi driver Liu Chunfa said. "I have attended several meetings with police lecturers," he added. "They told us if we report suspicious people, like believers in (the outlawed spiritual group) Falun Gong, we could get a 2,000-yuan ($250) reward."
The closed-door party get-together no longer rivets the nation as it did under Mao Zedong. It remains important, though.
The Communist Party has "moved from being Big Brother to big bother, but this congress is an opportunity to remind people: 'We are still a big deal,' " said Russell Leigh Moses, a Beijing-based analyst of Chinese affairs. The state and party "see the congress as an opportunity to make people stand up straight and pay attention, which is difficult in this hypereconomic and apolitical society."
The congress also will be filled with warnings for Taiwan, where President Chen Shui-bian is trying to distance the island from mainland China through a proposed referendum. It calls for the island to drop the name Republic of China and apply for United Nations membership as Taiwan.
The party has called for China to "oppose and repulse separatist activities for 'Taiwan independence,' " China's official Xinhua news agency reported.