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 pres¬ent 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 ideol¬ogy and illustrate the processes of inclusion and exclusion through lan¬guage. 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 affilia¬tion, 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.