Open Science means opening up science through transparency in the research process and participation of new actors in research and innovation. Many research performing organisations (RPOs) are interested in or have already set out to strengthen Open Science at their institution. To facilitate top-down engagement from institutional leaders and culture change we are currently developing Road2Openness (R2O). R2O is a web-based assessment tool that helps institutions to evaluate their current Open Science activities and supports them with recommendations for a strategic opening to develop institutional training, infrastructure and incentive systems for Open Science. We have partnered with three universities in Germany to co-develop and pilot the tool. In this talk, we will present the idea behind the tool, how it can be used by RPOs and the results from the pilot project.