Studies on the linguistic identity of multilingual speakers engaged in English as a Lingua Franca (ELF) interactions have continued to grow in the past 20 years. This paper was aimed at contributing to this line of research by studying interactional data to investigate the construction and negotiation of linguistic identities among multilingual speakers of English. Data was collected from 38 ELF interactions in a university classroom located in South Korea. The analysis shows that the students' linguistic identity in relation to English was made relevant consequent to the interactional exploitation of the two interrelated social constructs of phonology and nationality (i.e. being foreign). The findings suggest that these multilingual students negotiate and build one's linguistic identity by evaluating different ways of speaking English which in turn influence their own linguistic use. The study helps us understand how normative expectations or beliefs are expressed at the level of interaction and underscores the need for ELF awareness and development of related pedagogical tools for empowering these group of students.