Situated learning theory maintains that there is a relationship between learning and the social situation in which it occurs; learning is embedded in activity, context and culture. In terms of professional learning for teachers, this implies that effective learning takes place within a community where experts and novices meet and where practice is modelled; such a community needs to be deeply relevant to everyday practice in the classroom. In this paper, we discuss Computing At School, a grass-roots organisation that has grown up over the last 10 years through teacher communities, and also with broad support of academia and industry. In a time of increased interest in the inclusion of computer science in school curricular, Computing At School is a community of practice of all teachers affected by curriculum change in Computing and models an innovative approach to professional learning that is based on community and support. We describe here how Computing At School draws on situated learning theory to contribute to the development of Computing in the curriculum, evidencing both the journey and lessons learned.