Luxembourg often has been classified as a ‘triglossic’ country in sociolinguistic literature, due to Luxembourgish being used predominantly for spoken functions and French and German for written functions. However, language use in late modern Luxembourg is characterized by increased levels of spoken French coupled with the growing presence of written Luxembourgish in the public sphere, thus altering certain long-standing patterns of language use. In this context, Luxembourgish is often framed as an important marker of authenticity and national identity in language ideological debates. At the same time, the ideological positioning of Luxembourgish as the national language stands in tension with varying levels of uncertainty regarding writing conventions in Luxembourgish, particularly in more formal contexts. Based on the analysis of metalinguistic comments from the focus group data, this article examines how the participants discursively construct Luxembourgish in their negotiation between positioning Luxembourgish as the national language whilst also describing it as not being a fully-fledged standardized language. On a broader scale, this paper contributes to language ideological research that explores the construction of national languages as well as the relationship between the standard language ideology and the one-nation one-language ideology.