La Courneuve, France — It was a huge festival. More than 600,000 people danced to live music, rode on ferris wheels - and heard about workers' rights and socialist paradise.
The occasion was last weekend's two-day ''Fete de l'Humanite,'' the carnival organized here every year by the French Communist Party. That the party could put on such a massive affair with such high attendance shows how strong and imbedded the party remains in French society.
But the festival only masked profound problems facing the party. In many ways , French Communists are on the defensive, isolated and divided.
This might seem odd for a party that came to power in 1981 in France's first leftist government in more than two decades. As the junior partner in President Francois Mitterrand's Socialist-dominated coalition, though, the Communists are facing a dilemma.
The party wants to show it can help govern responsibly. But that means supporting a government that has made fighting inflation and increasing faltering industrial investment more of a priority than easing the plight of the country's 2 million plus unemployed.
Even before it entered the government, the Communist Party was in a tight spot. It had slipped from 22 to 15 percent of the vote in the 1981 election.
The decline forced the Communists to relinquish to the Socialists the dominant position in the French left that they have held for most of the postwar era, and accept the junior role in the Socialist-led government. There are only four Communist ministers in Mr. Mitterrand's government, and they hold such relatively low-profile posts as transportation and health.
Today, polls show that the party's share of the vote would fall to 12 percent if elections were held now. This further reduced role was illustrated by the attitude of many who attended the festival.
''I am not a militant,'' one young man said, echoing the statements of many others who were enjoying the sunshine and music. ''I came to have a good time.''
While this working-class youth might very well have been an active Communist a few years back, he now says the French Communist Party no longer relates to his needs.
''I am not looking for a struggle,'' he said.
According to many political analysts, this sentiment illustrates the party's problems. Its doctrinaire approach has become outdated in an increasingly modern France.
Unlike fellow Italian and Spanish Communists who have embraced an ill-defined ''Eurocommunism,'' the French party under Georges Marchais has stuck to a pro-Soviet line, refusing to condemn Soviet intervention in Afghanistan and martial law in Poland.
At the same time, while other European parties have become more flexible and less vitriolic in defining their communism, the French Communists have remained firmly tied to overthrowing the entire capitalist system. This point of view does not sit well with many workers who have become better off during France's rapid post-World War II industrialization.
Mr. Marchais has also retained the principle of ''democratic centralism,'' requiring members to accept the leadership's decisions without question.
This centralism, internally and externally, has splintered the party. Several thousand dissidents have left the party and are publishing a weekly journal, Rencontres Communistes, that demands more democracy in the party and greater freedom from Moscow.
''I finally decided it was time to dissociate ourselves from the authoritarian, secret practices that have come to characterize the party,'' Henri Fiszbin, Rencontres Communistes' leader, told the Monitor. ''The party is unable to take a stand independent of the Soviet Union.''
All the same, Fiszbin and his followers refused to join the Socialist Party. ''The history of France reveals that workers' movements have always had their political opinions expressed by the Communist Party,'' Fiszbin explained.
To be sure, the French Communist Party is firmly rooted in French history. It benefited from its undeniably courageous resistance record during the Nazi occupation. Through the 1940s and '50s, it maintained a distinct image amid the political fragmentation and factionalism of the Fourth Republic.
While the Socialist Party struggled to shed its reputation as a Parisian parlor reformer, the Communists earned high marks as honest, efficient administrators responsive to local needs, and provided a sense of ''belonging'' for their working-class followers.
Now this has all changed. Under Mr. Mitterrand, the Socialists have succeeded in painting themselves as much more reasonable than the Communists. As a result, they have attracted millions of votes away from the Communists, reversing the balance of power on the left.
But one cannot write off the Communists. They continue to hold tremendous power in the trade unions through their domination of France's largest union, the Confederation Generale du Travail (CGT).
It was this power that forced Mr. Mitterrand to include the Communists in his government. He preferred to keep the party safely under his wing rather than see it wreck Socialist rule with a series of strikes.
For the most part this strategy has worked so far. The Communists have been loyal partners, rarely raising their profile to criticize the government.
Recently, though, the Communists have begun to distance themselves somewhat from the Socialists as France's economic difficulties have increased. Mr. Marchais pointedly criticized the government for imposing a wage freeze.
But Mr. Marchais is not ready to pull his party out of the coalition just yet. At the Fete de l'Humanite, he reaffirmed his support in general for the government's austerity program.
''No one can honestly deny that the new majority elected in 1981 has a positive balance sheet,'' he said. This statement echoed the recent restrained language of Henry Krasucki, the Communist secretary-general of the CGT, who has refrained from calling for strikes because of the government's wage freeze.
Observers say the Communists will not stay tamed and tied up forever in a minor role in the government. The success of Mitterrand's government may depend on the result of a possible Socialist-Communist split.