Portugal is a democratic republic ruled by the constitution of 1976 with Lisbon, the nation's largest city, as its capital. The four main governing components are the president of the republic, the parliament, the government, and the courts. The constitution grants the division or separation of powers among legislative, executive and judicial branches. Portugal like most European countries has no state religion, making it a secular state.

The president, who is elected to a five-year term, has a supervising non-executive role. The current President is Aníbal Cavaco Silva.

The national and regional governments and the Portuguese parliament, are dominated by two political parties, the Socialist Party and the Social Democratic Party. Minority parties Unitarian Democratic Coalition (Portuguese Communist Party plus Ecologist Party "The Greens"), Bloco de Esquerda (The Left Bloc) and CDS-PP (Popular Party) are also represented in the parliament and local governments.