This paper presents and discusses the results of OnAir, a European project on Media Education funded by the European Commission. This two-year project aimed at collecting, documenting, and developing media education practices across Europe, especially in Belgium, Bulgaria, Italy, Lithuania, Poland, and Romania. In particular, the paper focuses on the role of documentation in improving teachers' practical knowledge and highlights the challenging aspects at stake in this process. The analysis of collected data reveals that documentation of media education practices is often poor both in terms of information about instructional practices and in teacher reflection on their actions. Stronger collaboration between teachers and researchers may be needed to support the kind of careful documentation that leads to effective practice. The development of adequate tools that teachers can easily use during their own activities may also facilitate improved levels of documentation. (Contains 2 tables, 2 figures, and 1 footnote.)