This paper explores the link between explicit Luxembourgish language policy and the actual practices as well as expressed attitudes of a group of speakers of Luxembourgish, with the aim of studying the role of World War II in the advancement of Luxembourgish as Luxembourg’s national language. The first two sections introduce the theoretical approach of the paper and provide an overview of the history and present situation of Luxembourg and Luxembourgish. The following two sections present the findings of a sociolinguistic study of language choice, language values and identities, and linguistic (in)security among a group of Luxembourgish letter-writers, as well as recent interview data provided by the sole surviving correspondent. The final section brings together these results and the claims made regarding the role of World War II in the changing status of Luxembourgish and points out the complexity of this discussion.