Social presence is considered an important quality in computer-mediated communication as it promotes willingness in learners to take risks through participation in interpersonal exchanges (Kehrwald, 2008) and makes communication more natural (Lowenthal, 2010). While social presence has mostly been investigated through questionnaire data and quantitative content analysis of online interactions based on a set of predefined indicators, in a smaller number of studies the concept has also been investigated through qualitative analysis of interviews (Kehrwald, 2008, 2010). Yet studies that bring together multiple sources of data collection and examine multimodal language learning contexts are almost non-existent. In this paper, the theory of social presence is employed to explicate language learners' online multimodal communication using a case study approach. Multiple sources of data were collected, including interviews, open-ended and closed post-task questionnaires, stimulated reflection and recordings of video interactions. The main findings of the study included an innovative social presence framework developed for the analysis of online multimodal language learner interactions (Satar, 2010), which can be used in further qualitative and exploratory research. It also has potential applicability for educators to develop strategies for language learners to guide them in creating and transmitting their social presence. The focus of this article is a cross-case analysis for one of the components of social presence, sustaining interaction, bringing together social presence theory, interactional sociolinguistics and multimodal interaction analysis. Finally, strategies are proposed for language learners on how to sustain their online multimodal interactions.