In 1973, amidst escalating social discontent and a pressing need for political change in Portugal, the Portuguese Socialist Party (Partido Socialista, PS) was established in Bad Münstereifel, Germany. The party was formed by a cadre of Portuguese intellectuals and political exiles who had fled the oppressive Estado Novo regime, which had ruled Portugal since 1933. These individuals recognized the necessity to create a viable political alternative that could promote democracy and social justice in their homeland.

The founding congress brought together prominent figures, including Mário Soares, who later became the first Socialist Prime Minister of Portugal after the Carnation Revolution in 1974. The leaders laid out a platform rooted in socialist principles, advocating for workers' rights, social equality, and the establishment of a democratic government. Their vision sought to engage the Portuguese populace and build a comprehensive strategy to oppose the existing authoritarian political structure.

The creation of the PS was a significant step in consolidating the fragmented leftist movement in Portugal, providing a structured political party that could unify various factions under socialist ideals. It marked a pivotal moment of solidarity among those striving for freedom and reform, and it set the stage for the radical changes that would soon follow the Carnation Revolution, which ultimately led to the collapse of the Estado Novo regime.