Prodded by the Communists, the Radicals and Socialists aligned in 1936 with the Confederation of Chilean Workers (Confederación de Trabajadores de Chile--CTCh), a by-product of union growth and solidarity, to forge the Popular Front. The Popular Front was given impetus by Alessandri's crushing of a railroad strike that year. The coalition also included the old Democrat Party, which was gradually supplanted by the Socialist Party until the former disappeared in the early 1940s. Similar to multiparty alliances in Europe and to populist coalitions in Latin America, the Popular Front galvanized the middle and working classes on behalf of democracy, social welfare, and industrialization. Its redistributive, populist slogan was "Bread, Roof, and Overcoat," coined by the 1932 Socialist Republic.

The Popular Front barely beat Alessandri's would-be rightist successor in the presidential contest of 1938 with 50.3 percent of the vote. One key to the Popular Front's victory was its nomination of a mild-mannered Radical, Pedro Aguirre Cerda, rather than the inflammatory Socialist, Marmaduke Grove. The other key was a bizarre sequence of events in which a group of Chilean fascists (members of the National Socialist Movement), backing Ibáñez's independent bid for the presidency, staged an unsuccessful putsch on the eve of the election. The slaughter of the putschists by forces of the Alessandri government prompted the fascists to throw their votes to the Popular Front. Although not numerous, those ballots put the Popular Front over the top.

The incongruous alignment of Nazis behind the antifascist Popular Front showed how far Chilean politicians would go to subordinate ideology to electoral considerations. Thus, a coalition that included Socialists and Communists captured the presidency quite early in twentieth-century Chile. Future president Salvador Allende served briefly as minister of health in this period.

Running under the slogan "To Govern Is to Educate," Aguirre Cerda (president, 1938-41) won an electoral majority in 1938. However, less than 5 percent of the national population actually voted for him. Until the rapid expansion of the electorate in the 1950s, less than 10 percent of the national population voted for presidential candidates. Only literate males over the age of twenty-one could vote in most elections until the 1950s; of those eligible to vote, approximately 50 percent usually registered, and the vast majority of those registered cast ballots. Women were allowed to exercise the franchise in installments, first for municipal elections in 1935, then for congressional contests in 1951, and finally for presidential races in 1952.