The Communist International (Comintern), also known as the Third International, was an international organization founded in 1919 that advocated world communism, headed by the Soviet Union. The Comintern resolved at its Second Congress to "struggle by all available means, including armed force, for the overthrow of the international bourgeoisie and the creation of an international Soviet republic as a transition stage to the complete abolition of the state". The Comintern was preceded by the 1916 dissolution of the Second International.

The Comintern held seven World Congresses in Moscow between 1919 and 1935. During that period, it also conducted thirteen Enlarged Plenums of its governing Executive Committee, which had much the same function as the somewhat larger and more grandiose Congresses. Joseph Stalin, leader of the Soviet Union, dissolved the Comintern in 1943 to avoid antagonizing his allies in the later years of World War II, the United States and the United Kingdom. It was succeeded by the 1947 Cominform.

The Portuguese Communist Party (Portuguese: Partido Comunista Português, pronounced [pɐɾˈtiðu kumuˈniʃtɐ puɾtuˈɣeʃ], PCP) is a communist, Marxist–Leninist political party in Portugal based upon democratic centralism. The party also considers itself patriotic and internationalist, and it is characterized as being between the left-wing and far-left on the political spectrum.The Party was founded in 1921, establishing contacts with the Communist International (Comintern) in 1922, and became in 1923 the Portuguese section of the Comintern. Made illegal after a coup in the late 1920s, the PCP played a major role in the opposition to the dictatorial regime of António de Oliveira Salazar. During the five-decades-long dictatorship, the party was constantly suppressed by the political police, the PIDE, which forced its members to live in clandestine status under the threat of arrest, torture, and murder. After the Carnation Revolution in 1974, which overthrew the 48-year regime, the 36 members of party's Central Committee had, in the aggregate, experienced more than 300 years in jail.After the end of the dictatorship, the party became a major political force of the new democratic regime. One of its goals, according to the party is to maintain its "vanguard role in the service of the class interests of the workers". Currently, the PCP is the fifth largest in the Portuguese Assembly of the Republic, where it holds 6 of the 230 assembly seats.The Party publishes the weekly Avante!, founded in 1931. Its youth organization is the Portuguese Communist Youth, a member of the World Federation of Democratic Youth.