When looking at the calendar of events under the 2018 Austrian presidency of the European Union, we get the impression Open Science is dominating the STI agenda and research policy discussions. However, when we look around us here in Austria (and in many other European countries), we see a lot of wonderful initiatives and bottom-up activities, there is commitment of policy makers and research funding and performing organisations, but the topic of Open Science is still highly distributed across institutions without a national strategy let alone a coherent legislation. Whereas there is a strong push from the EU to foster a multi-dimensional transition to Open Science, there is no common baseline for how to implement Open Science nationally. In my talk I will report on the outcomes of mutual learning exercise (MLE) that was set up by the Commission and 13 countries to address this. In this Open Science MLE we embraced a hands-on, ‘learning by doing’ approach supported by external expertise. Concrete examples, models, best practices and knowledge exchanges fostered broader understanding of the implications and benefits of Open Science strategies, covering key elements of the European Open Science Agenda and thus the needs for Assessing the potential of non-traditional metrics or ‘altmetrics’ while considering matters of transparency and responsibility Creating the right incentives and rewards for a range of actors to engage in Open Science activities Developing guidelines for designing and implementing national policies and cross-national cooperation for Open Science. Based on the outcomes of the MLE, I will then address several pressing issues and challenges of campaigning for Open Science and take up some of the topics that were discussed over the last days at this very conference, most importantly the questions, how we can ensure to measure what matters, and what is needed in terms of best practices and role models to foster a transition to Open Science that rests on close cooperation of all relevant actors in the STI ecosystem.