It is often stressed that the pedagogic models and approaches of Collaborative Online Learning support a learner's shared knowledge building within collaborating groups of learners, the individual construction of knowledge and the formation of an ongoing learning Community of Practice. Based on a recent case study of a Danish Master's programme, this paper will demonstrate that the emerging collaborative practice displays tendencies contrary to the generally accepted assumptions. The outcome is not only based on the models and their attributes, it is also affected by the emerging practice itself and the interaction among the participants during a course. From this perspective, it is relevant to look at which possibilities and obstacles teachers encounter when they try to detect slowly emerging tendencies that may lead to major misinterpretations of the subject matter and marginalize or even exclude students from participating in the learning Community of Practice. In conclusion, the case study will identify the slowly emerging tendencies that may be detected and observed at an early stage and thus indicate areas in on-line learning environments that require special attention.