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 lecturer seeking to encourage social construction of understanding through online dialogue and proposes an alternative which extends the principles of Community of Inquiry theory. It describes a design-based research project which focuses on the dialogue itself in a university learning environment, and on the development of facilitation techniques which will encourage it to flourish.