[11] The LSAP is particularly strong in the south of the country,[11] controlling most of the mayoralties in the large towns of the Red Lands.

[12] On 5 November 1937, the Party joined the government for the first time, in a coalition under Prime Minister Pierre Dupong.

In the first election after the war, in 1945, the LSAP was the big loser, falling to 26% of the vote, but remained in the National Union Government, along with all other parties.

In March 1971, centrist elements, led by Cravatte, split to create the Social Democratic Party.

In this legislative period, the LSAP held their famous energy conference, and decided a moratorium for the atomic power station of Remerschen.

[15] Following the 2013 general election, the LSAP was in a three-party Bettel–Schneider government with the Democratic Party and The Greens, with the Democratic Party's Xavier Bettel serving as Prime Minister and Etienne Schneider of the LSAP as Deputy Prime Minister.