This paper reports on a study concerning a MOOC designed to support Greek language teachers in secondary education schools towards designing and using collaborative writing activities with Google Docs in their classroom. The principles that determined the particular MOOC design framework were directed by three dimensions of teacher participation: a) engagement b) peer interaction and mutual support and c) collaborative creation of educational artefacts. A total of 566 language teachers from secondary education schools were enrolled in this MOOC, which achieved a completion rate of 57.6%. We used a mixed method that combines the analysis of teachers' engagement through platform records and their responses to a specific questionnaire. The results provided supportive evidence that the design framework was effective towards promoting teachers' active engagement, peer interaction and support, and development of learning design abilities to integrate collaborative writing with Google Docs in their classroom. In addition, the analysis showed that the majority of participants conceptualized this MOOC as an efficient environment for their professional development. [For the complete proceedings, see ED590269.]