Abstract. This paper investigates the use of ontologies in processes of collaborative learning and knowledge generation. The creation and use of ontologies is analysed from an activity theoretical perspective in order to understand processes of shared conceptualization as well as the role of ontologies in processes of change and transformation. Scenarios of ontology-based collaborative learning and knowledge-creation are presented. This work is based on the cultural-historical activity theory, providing a theoretical framework (1) for understanding processes of knowledge-creation which take place when generating and using ontologies and (2) to investigate the dynamic relationship (coupling) between individual learning and the transformation of a community.