Hundreds of thousands of French workers are expected to join the country's second nationwide strike in two months.
Unions are protesting against President Nicolas Sarkozy's economic policies. Unemployment has reached two million and is expected to rise further.
Demonstrations are planned in about 200 towns and cities on Thursday. Schools are to close and public transport faces disruption.
Organisers hope the protest may be bigger than one in January, when about a million people joined protests.
The unions are urging the government to do more to protect jobs and wages.
Three-quarters of French people support the strike, claiming the 2.4 billion euros offered by the government earlier this year is not enough.
Protesters are also calling on the president to scrap his plans to cut public-sector jobs and to reverse tax cuts.
President Sarkozy says he understands the plight of the workers but there is little more his government can do.
Unemployment is likely to shoot up to 10% in the next 12 months with a further 350,000 layoffs expected by the end of this year.
Private-sector workers from the beleaguered car industry, oil and retail sectors will also be on the streets.