The interpenetration of nationalism and socialism is a seminal problem for understanding 20th century labour movement history. This article approaches the issue of ideological interpenetration by way of a close examination of the relationship between minority nationalism and socialist unity during a formative phase for the Finnish labour movement in the post-war period. More precisely, the article investigates the Swedish-speaking minority within the Finnish labour movement and its attempt to unify different ideological factions in the labour movement through minority nationalism. The article contributes to the study of the relation between socialism and nationalism by extending the discussion to include national minorities and their relation to the socialist labour movement. The main theoretical innovation of the article is the concept of socialist minority nationalism. This concept will function as a heuristic tool for analysing the intersection of nationalism and socialist class-consciousness within the Finnish labour movement. The Swedish-speaking agents of the Finnish labour movement, and their socialist Finland-Swedish identity-project, has hitherto been neglected in Finnish labour history. Through historical investigations of national or ethnic minorities, or other past and present marginalized groups and individuals in labour history, it is possible to problematize the hegemonic historical narratives of the majority.