Informed by linguistic ecological theory and the notion of identity, this study investigates language uses and identity construction in interactions among students with different linguistic and cultural backgrounds in a multilingual university. Individual and focus-group interviews were conducted with two groups of students: Hong Kong (HK) and mainland Chinese students. The findings indicate that, while different languages position their speakers in different symbolic spaces, language users employ a variety of languages for different identification purposes, and exercise symbolic power in various ways in order to be heard and respected. It is also found that language often plays a substantial role in achieving a sense of intimacy among group members and that the huge inherent differences, despite the umbrella of "unity" between HK and mainland China, lead to a mutual non-identification between HK and mainland students. The study extends understandings of the interconnected relations of languages and context. (Contains 2 tables.)