The development of smartphones and mobile Internet have advanced tremendously since 2000 and have made the access to communication increasingly available in diverse settings, including classrooms. Today, smartphones are used in classrooms as part of both on- and off-task activities. For multilingual participants, this communication involves several languages. Previous research shows that classrooms are often oriented to and jointly constructed as monolingual settings in which participants orient to the language of instruction. In the research reported here, I focus on the ways that multilingual participants orient to and use mobile digital technology to co-construct multilingual identities in these classrooms, that is, how participants can, in-and-through the use of mobile communication, actively construct multilingual identities and bring them into the classroom. However, the mobile interactions also influence and contribute to classroom interactions and vice versa. Nevertheless, the digitally-local multilingual identity that is co-constructed and expressed in mobile interactions appears not to be problematized in the same manner as explicitly multilingual turns in the non-digital classroom may be oriented to as interactionally problematic. The verbal, non-digital, classroom becomes—in the interactional spaces afforded by the mobile communication—multilingual, as the participants co-construct multilingual identities in-and-through their mediated interactions.