This exploratory case study considers the interpersonal dimension of collaborative learning in an online graduate community that is based on a cohort approach to education which is characterized by the social construction of knowledge. Discourse data from two graduate courses are analyzed for interpersonal elements associated with social presence through the lens of Systemic Functional Linguistics. A general profile of the interpersonal dimension of the learning community is provided along with a consideration of cognitive engagement and the interpersonal dynamics of two dilemmatic situations. Data analyses indicate that social presence is much more than social chat and that the nature of the collaborative learning process is deeply intertwined with interpersonal engagement among participants.