This article reports from a project on the role of public libraries in language assimilation policies directed against the Meänkieli-speaking Tornedalian minority in the far north of Sweden during the first half of the 20th century. As libraries in the Torne Valley area, bordering on Finland, were maintained under state control, they became tools in the near eradication of Meänkieli in a complex set of policies that were in effect until 1957, promoting a uniform Swedish language and culture. Building on sociological conflict theory and the analysis of unpublished local documentation, the article brings to light conditions previously unknown about the Swedish public libraries in the northernmost part of the country. The article concludes by reflecting on the role of Swedish libraries today as important tools for the revitalization of Meänkieli, aimed at strengthening the identity and visibility of the Tornedalian minority.