The Portuguese Constituent Assembly election, 1975 was carried out in Portugal on 25 April 1975, exactly one year after the Carnation Revolution and was the first free election in fifty years, the first in the new democratic regime created after the revolution which made the turnout the highest ever.
The main aim of the election was the election of a Constituent Assembly, in order to write a new Constitution to replace the Estado Novo regime's authoritarian Constitution of 1933 and so, the elected parliament had a single year mandate and no government was based on the parliament support, the country continued to be governed by a military-civilian provisional administration.
The election was, perhaps surprisingly, won by the Socialist Party. The Social Democratic Party was the second most voted party, defending a project that it would soon abandon, the social-democracy becoming the major right-wing party in the country a few years after. The parliament had a large majority of parties defending socialist or "democratic socialist" ideas and the Constitution, approved one year after, reflected such influence. The Portuguese Communist Party achieved a surprisingly low voting, considering the overwhelming support in the south of the country and the radical turn to the left of the revolutionary process after the failed fascist coup, one month before.