The Socialist Party was founded in 1918 as the political arm of the syndicalist trade union National Workers' Secretariat (Nationaal Arbeiders' Secretariaat).
All its founders had their personal background in the free socialist movement of Ferdinand Domela Nieuwenhuis.
The SP wanted to abolish indirect taxation and implement a system of strongly progressive income taxes.
It wanted to end child labour and night shifts and reduce the working day to eight hours.
It wanted to replace monarchy by a republic, abolish secret diplomacy, the army and the navy.