Whereas a reasonable body of research now exists on the use of networked learning and learning communities in higher education, especially in post-graduate studies, less is known about their use in other sectors of education, such as continuous vocational education and training. This research focuses on an example of the use of online learning communities for teachers' professional development – eTwinning Learning Events. It looks at how the online community supports the development of teachers’ competence and practice in online collaboration, how social aspects contribute to this discourse and the impact of facilitation, guidance and orchestration. Action research was used to follow and influence the development of a Learning Event (LE) entitled 'Exploiting Web 2.0: eTwinning and Collaboration' first held in April 2010. Applying the Community of Inquiry (CoI) framework (Garrison, Anderson, & Archer, 2000) we examined the interrelated dimensions of cognitive presence, social presence and teaching presence. The analysis suggested that skills were developed in the use of the web 2.0 tools, however there was less impact on teaching competence and practice, social interaction was important but seen as second place to the cognitive activities and the burgeoning community failed to fully develop. The event was rerun in the autumn and an analysis of the data collected through a participant questionnaire, interviews and the coding of the messages in the discussion forums suggested that the changes applied had had a positive impact on the learning, the social interaction and the contribution of the tutors. Cognitive presence had been reinforced through practical experience and a final reflection activity, with evidence of critical thinking emerging in the participants' discourse. A Staff room for informal knowledge sharing had engendered a good social presence and a community had emerged that thrived for as long as it served the purpose of learning. The teaching presence had been ensured through additional tutoring at key points, to provide feedback and encourage reflection, and the gradual emergence of mutual support from peers. The results of the research will contribute to our understanding of how the cognitive, social and teaching aspects of an online learning community are interrelated and combine to offer a valuable learning experience in support of professional development.