The Liberal League (Luxembourgish: Liberal Liga, French: Ligue Libérale, German: Liberalen Liga) was a political party in Luxembourg between 1904 and 1925. It was the indirect predecessor of the Democratic Party (DP), which has been one of the three major parties in Luxembourg since the Second World War.
For the first decade of its existence, the Liberal League maintained the liberal dominance under Prime Minister Paul Eyschen. In 1908, they formed an alliance with the Socialists, leading to confrontations with the Party of the Right over secularism. During the First World War, the party lost much of its advantage, and was replaced as the dominant party by the Party of the Right. In the early 1920s, riven by rivalries between its classical liberal and progressive wings, the party collapsed.
The liberal Liberal League was founded in 1904 as a formalisation of the decentralised ideological alliance already existing within the Chamber of Deputies, under the leadership of the classical liberal Robert Brasseur. The liberal faction was predominantly supported by the entrepreneurial and middle classes. Nonetheless, in 1908, the Liberal League and the Socialist Party (formed in 1902) formed a seemingly unlikely alliance, called the 'Left Bloc' (Bloc de la Gauche) in Esch-sur-Alzette. The main aim of this alliance was to ensure and extend the secularism of the state, which they saw as being under attack from the overtly Roman Catholic conservative grouping; secularisation of the school system was the major policy on which they fought the elections of 1908, 1911, and 1912.