Social construction of understanding has long been a significant underlying principle of learning and teaching, and while there are many models for the design of online activities to promote this, there are considerably fewer models for the facilitation of such dialogue. This paper examines some of these facilitation models from the point of view of a university tutor seeking to encourage social construction of understanding through online dialogue, and proposes an alternative which extends the principles of community of inquiry theory. It unpacks conceptions of community and dialogue in the context of learning and teaching and describes a research project whose purpose is to develop and iteratively test a professional development intervention, which will help university tutors to facilitate a dialogic approach to learning online. (Contains 1 figure.)