The job interview data I analyse here illustrate how applicants and assessment committees negotiate understanding through Danish as a shared linguistic resource. The chapter consists of four parts. First, I present examples from previous research on job interviews where linguistic and cultural assessments take place (Kirilova, 2013; Roberts & Campbell, 2006). I draw on language ideology (Irvine & Gal, 2000; Silverstein, 2006) as a theoretical framework and discuss the notions of gatekeeping, membership ascription and shibboleths to operationalise language ideology and illustrate the processes of inclusion and exclusion through language. Second, I address the use of conventional expressions as shibboleths in the negotiation of lingua-cultural co-membership. I suggest that when language users at a beginner’s level use conventional expressions in the communication with language users at a more advanced linguistic level (or when L2 beginners communicate with L1 users), conventional expressions may help L2 users to communicate more effectively. In the third part, I present data and methods, and analyse extracts of one job interview where the applicant communicates through a large number of conventional expressions. I argue that conventional expressions may not only enable linguistic understanding, but also support the social relationship between the interlocutors thus playing an important role for their mutual affiliation, especially in high-stakes gatekeeping contexts. In the last part, I return to the language ideological framework for a broader discussion and directions for future research.