Hundreds of thousands of demonstrators are expected to take part in marches across France as five unions join strikes and protests in a national day of action.
The protests began in September with high school students complaining about poor conditions and resources in education, but have spread to include the so-called "yellow vest" movement and workers.
Authorities expect 500,000 to 700,000 demonstrators to join marches, with tens of thousands more in Paris alone, in a day billed by one union leader as "a great day of convergence".
The five unions have combined forces across the public and private sector, with demands for higher wages to combat the cost of living and protected public services.
Interior Minister Laurent Nuñez has said that 70,000 police and gendarmes are being deployed, vowing "an extremely firm response" to any potential outbreaks of violence.
More than 250 separate actions are planned for 5 November, with some disruption reported in schools, hospitals and public transport.
Workers have also been asked to halt production at oil refineries, and France is expected to import more electricity than it produces on Thursday because of disruption at nuclear plants.
A coalition of unions has urged workers, pensioners and young people to join Thursday's day of strikes to intensify pressure on the government. In particular they are seeking a rise in the minimum wage, or Smic , which is currently €12.31 (£10) an hour.
The head of the CFDT union, Marylise Léon, complained that it was not just the minimum wage that needed to increase: "We are asking for a net increase of €100 a month."
The government has sought to appease public anger over rising prices, bringing down the cost of fuel by releasing 10 million barrels of diesel from strategic reserves. Ministers have also promised school students to reform the unpopular Parcoursup university admissions platform and eventually replace it by 2028.
Large numbers are expected on the streets, especially in the capital.
One union leader Sophie Binet, who called it the "great day of convergence", added: "The time has come to take the mobilisation to the next level; the strike must take over."
Léon said she would be happy if 800,000 people turned out.
Union leaders have complained that recent marches have been kept away from the centre of Paris, because of violence that broke out in towns and cities on 17 October and led to more than 2,000 stores being looted and historic buildings being set on fire.
Thursday's march will be allowed through the centre of Paris, although not along the route proposed by the unions between Place de la Bastille and Place de la Concorde, which would have taken protesters near the National Assembly, the Élysée Palace, and the prime minister's residence at Hôtel Matignon.
Instead, the march is set to follow another central route from Place de la République to Place de la Nation. The CFDT union complained that getting court approval for the route only on Wednesday evening made organising the march more difficult.
The last big mobilisation at the weekend passed off with relatively little violence, and the interior minister said the police deployment would be on a similar scale on Thursday. Nuñez has spoken of three potential risks on Thursday, from radical left "black blocs" groups and looting to wildcat marches without union authorisation.
