This chapter discusses the role of multilingualism and multisemioticity as key resources in communication in contemporary interest-driven social media. We approach social media as translocal arenas for social interaction and (trans)cultural activities (Leppänen 2008, 2012; Kytölä in press) which complement and intertwine with participants’ offline realities in different ways. In particular, we show how the investigation of such activities can benefit from a multi-dimensional framework drawing on insights from several fields, including online ethnography, the study of multimodality, and research into computer-mediated discourse (CMD).