Language maintenance efforts aim to bolster attitudes towards endangered languages by providing them with a standard variety as a means to raise their status and prestige. However, the introduced variety can vary in its degrees of standardisation. This paper investigates whether varying degrees of standardisation surface in explicit attitudes towards standard varieties in endangered vernacular speech communities. Following sociolinguistic models of standardisation, we suggest that explicit attitudes towards the standard variety indicate its acceptance in vernacular speech communities, reflecting its overall degree of standardisation. We use the standardised Attitudes towards Language (AtoL) questionnaire to investigate explicit attitudes towards the respective standard varieties in two related vernacular speech communities—the Belgische Eifel in Belgium and the Éislek in Luxembourg. The vernacular of these speech communities, Moselle Franconian, is considered generally vulnerable (UNESCO), and the two speech communities have opted to introduce different standard varieties: Standard Luxembourgish in Luxembourg shows lower degrees of standardisation and is only partially implemented. In contrast, Standard German in the Belgian speech community is highly standardised and completely implemented. Results show that degrees of standardisation surface in speakers’ explicit attitudes. Our findings have important implications for the role of standardisation in language maintenance efforts.