Socialization into the workplace is a challenge faced by new foreign workers in multilingual societies. One underexplored factor in the process is code-switching. We presented a case study of how a Filipino migrant integrated into her Hong Kong workplace where the local veterans used code-switching at work. Conceptualizing the workplace as Communities of Practice (Wenger 1998), we employed Gee's (2011) model of discourse analysis to examine empirical workplace discourse. Our analysis suggests that for a newcomer, code-switching indicates desire of socialization, negotiation of membership, linguistic competence, and professional abilities, and that for a veteran, code-switching reveals situated identities, instantaneous relationships, openness to newcomers, and encouragement to them. We argue that code-switching is performed by foreign newcomers and local veterans for workplace socialization and mutual identification.