In this paper social semiotics, and systemic functional linguistics in particular, are used in order to identify registers of digital literacy in the use of virtual learning environments. The framework of social semiotics provides means to systemize and discuss digital literacy as a linguistic and semiotic issue. The following research question was investigated in the paper: What different registers of digital literacy could be identified when students and teachers communicate and interact in a VLE? The research question was answered by, initially, an application of social semiotics to virtual learning environments, and its relation to the knowledge domains of everyday, specialized and reflexive digital literacy. This application was then further developed, using an analysis of a course specific use of a virtual learning environment in a case study. The study identified discrepancies between the digital literacies of teachers, designers and students. These discrepancies mean that a shared semiotic register was sometimes difficult to maintain. The conclusion is that the designers and teachers as co-designers of virtual learning environments need a better understanding of everyday digital literacy in order to design more sufficient learning environments. The paper shows that digital literacy must be considered as a situated practice, and that it concerns functional and communicative competencies rather than acquiring a set of technical skills. (Contains 4 tables and 1 figure.)