The Popular Front (French: Front populaire, [fʁɔ̃ pɔpylɛːʁ] ^ⓘ) was an alliance of left-wing movements in France, including the French Communist Party (PCF), the socialist SFIO and the Radical-Socialist Republican Party, during the interwar period. Three months after the victory of the Spanish Popular Front, the Popular Front won the May 1936 legislative election, leading to the formation of a government first headed by SFIO leader Léon Blum and composed of republican and SFIO ministers.

Blum's government implemented various social reforms. The workers' movement welcomed this electoral victory by launching a general strike in May–June 1936, resulting in the negotiation of the Matignon Agreements, one of the cornerstones of social rights in France. All employees were assured a two-week paid vacation, and the rights of unions were strengthened. The socialist movement's euphoria was apparent in SFIO member Marceau Pivert's "Tout est possible!" (Everything is possible). However, the economy continued to stall, with 1938 production still not having recovered to 1929 levels, and higher wages had been neutralized by inflation. Businessmen took their funds overseas. Blum was forced to stop his reforms and devalue the franc. With the French Senate controlled by conservatives, Blum lost power in June 1937. The presidency of the cabinet was then taken over by Camille Chautemps, a Radical-Socialist, but Blum came back as President of the Council in March 1938, before being succeeded by Édouard Daladier, another Radical-Socialist, the next month. The Popular Front dissolved itself in autumn 1938, confronted by internal dissensions related to the Spanish Civil War (1936–1939), opposition of the right-wing, and the persistent effects of the Great Depression.

After one year of major activity, it lost its spirit by June 1937 and could only temporize as the European crisis worsened. The Socialists were forced out; only the Radical-Socialists and smaller left-republican parties were left. It failed to live up to the expectations of the left. The workers obtained major new rights, but their 48 percent increase in wages was offset by a 46 percent rise in prices. Unemployment remained high, and overall industrial production was stagnant. Industry had great difficulty adjusting to the imposition of a 40-hour workweek, which caused serious disruptions while France was desperately trying to catch up with Germany in military production. France joined other nations and bitterly disappointed many French leftists in refusing to help the Spanish Republicans in the Spanish Civil War, partly because the right threatened another civil war in France itself.

There are various reasons for the formation of the Popular Front and its subsequent electoral victory, including the economic crisis caused by the Great Depression, which affected France starting in 1931, financial scandals and the instability of the Chamber of Deputies elected in 1932 that had weakened the ruling parties, the rise of Adolf Hitler in Nazi Germany, the growth of violent far-right leagues in France and in general of fascist-related parties and organisations (Marcel Bucard's Mouvement franciste, which was subsidised by Italian leader Benito Mussolini, Neo-Socialism etc.)

The elections of 1932 had resulted in a victory for the two largest parties of the left, the Marxist SFIO and the Radical-Socialist PRRRS, as well as several smaller parties ideologically close to Radicalism (an electoral pact known as the Cartel des Gauches); the Communist Party had run on its own, accusing the Socialists of social-fascism and opposing the subsequent centre-left governments. However, major differences between the SFIO and PRRRS prevented them from forming a cabinet together, as all had expected, leaving France governed by a series of short-lived cabinets formed exclusively of the six Radical parties.

The Socialist Party reliably granted its confidence to these cabinets but fundamentally disagreed with their budget cuts, and the various small liberal centre-right parties who agreed with the budget cuts refused to support centre-left governments in which they were not represented. With government paralyzed, tensions grew greater and greater both between the different parties in parliament and within public opinion. The tensions finally erupted into the infamous 6 February 1934 crisis in which massive riots by authoritarian paramilitary leagues caused the collapse of the Cartel. The Radical-Socialists and other republican centre-left parties accepted entry into a government dominated by the centre-right (the liberal conservative Democratic Alliance) and hard right (the Catholic conservative Republican Federation). The support by extreme-right paramilitaries for the National Unity government alarmed the left, which feared that plans to reform the constitution would lead to the abandonment of parliamentary government for an authoritarian regime, as had recently occurred in other European democracies.

The idea of a "Popular Front" therefore came simultaneously from three directions:

Thus, antifascism became the order of the day for a growing number of Communists, Socialists and Republicans as a result of a convergence of influences: the collapse of the centre-left coalition of 1932, the fear of the consequences of the 1934 riots and the broader European policy of the Comintern. Maurice Thorez, secretary general of the SFIC, was the first to call for the formation of a "Popular Front", first in the party press organ L'Humanité in 1934 and then in the Chamber of Deputies. The Radical-Socialists were at the time the largest party in the Chamber, and had often been the dominant party of government during the second half of the Third Republic.