WHY Open Science in Horizon 2020? Open Science (OS) offers researchers tools and workflows for transparency, reproducibility, dissemination and transfer of new knowledge. Ultimately, this can also have an impact on in research evaluation exercises, e.g. Research Excellence Framework (REF), set to demand greater “societal impact” in future, rather than just research output[1]. OS can also be an effective tool for research managers to transfer knowledge to society, and optimize the use and re-use by unforeseen collaborators. For funders, OS offers a better return on investment (ROI) for public funding, and underpins the EU Digital Agenda by measurably contributing to economic growth. This brief showcases why and how Open Science can optimize your Horizon 2020 proposal evaluation. WHO is this “BRIEF” for? This brief is developed through EC funding and specifically aimed at Horizon 2020 applicants and proposal writers seeking to comply with the Horizon 2020 Mandate (Grant Agreement article 29.1-6) and to optimize proposal evaluation and eventual societal impact of the resulting project. HOW to use the “BRIEF”? The text is NOT intended to be used verbatim as copy and paste contribution to your proposal. Instead, the brief presents suggested ways of formulating an impact section that answers the overarching political agendas and initiatives, as well as tips for ensuring that research results are effectively delivered to any users and the market place, across the various Horizon 2020 Pillars. The main text is generic, but some discipline-specific examples are included as examples, rather than covering all research fields. The footnotes also point to additional resources that will facilitate implementation to optimize project visibility and impact. Testing Brief impact on Evaluation Process: The brief was developed and tested with applicants of the funding calls below, and subsequently delivered through a series of training seminar series for Horizon 2020 National Contact Points (NCP) in Austia, Belgium, Denmark, Finland as part of FP7 FOSTER (Grant Agreement 612 425) Training Calendar. Horizon 2020, Pillar 1 Excellence: H2020-MSCA-ITN-2014 (3 consortia in Marine & Nannotech research) Horizon 2020, Pillar 3 Societal Challenges, SC-2 - Call BG-1-2015 Improving the preservation and sustainable exploitation of Atlantic marine ecosystems, https://ec.europa.eu/research/participants/portal/desktop/en/opportunities/h2020/topics/542-bg-01-2015.html (1 consortium); - Call BG-2-2015 Forecasting and anticipating effects of climate change on fisheries and aquaculture, https://ec.europa.eu/research/participants/portal/desktop/en/opportunities/h2020/topics/543-bg-02-2015.html (2 consortia); - Call EINFRA-1-2014 Managing, preserving and computing with big research data (that lead to succesful funding of EGI-ENGAGE https://www.egi.eu/about/egi-engage/), https://ec.europa.eu/research/participants/portal/desktop/en/opportunities/h2020/topics/335-einfra-1-2014.html (1 consortium). [1] Weighting of research impact confirmed for 2014 Research Excellence Framework http://www.hefce.ac.uk/news/newsarchive/2011/news62310.html , 2011