The Social Democratic League (Dutch: Sociaal-Democratische Bond, SDB) was a socialist political party in the Netherlands.

In 1878 they, led by Willem Ansigh, left the ANWV to found the Sociaal-Democratische Vereeniging (Social-Democratic Association; SDV).

It had branches in major cities like Amsterdam, The Hague, Haarlem and Rotterdam The SDB was founded in 1881 by members of the SDV and similar local socialist parties.

Domela Nieuwenhuis won the seat in the second round with the support from the Protestant Anti-Revolutionary Party, which preferred a socialist over a liberal MP.

[citation needed] This led to a split; during the SDB party conference of 1893 in Groningen, a majority voted to stop participating in the elections.

When the anarchist elements began to take full control of the SDB, important regional social democratic figures joined the group around Troelstra.

In 1901 the district of Schoterland elected the independent Socialist candidate, Geert van der Zwaag as its MP.

Before the Russian Revolution, the term social democrat, socialist and communist were used interchangeably to denote a Marxist ideology.

Important issues for the party were the prohibition of alcohol, the abolition of the army and the replacement of the monarchy with a republic and the independence of the Dutch East Indies.

In the 1890s the party began to win support in the poor rural province of Groningen and larger cities, like Amsterdam and Zaandam.