The workshop aims to establish the context for Open Science Policy and Research Assessment and to provide a brief overview of the importance of monitoring Open Science practices and policies, and to offer insights from the collective efforts of the OPUS, GraspOS, and PathOS projects. Open Science is the new way to conduct research. However, despite the growing adoption of Open Science principles, the research community is still struggling to keep up with fragmented research policies and the lack of incentives and recognition for researchers' activities. Each country may have its own national policy, institutions may have developed their own roadmaps, along with several national and European funders. These policies increasingly mandate Open Science practices, particularly Open Access to publications and research data management and sharing, which influences the research process and consequently the way research and researchers are assessed. This transformation intensifies the need for an evidence-based view of the evolution of Open Science and its impact in order to facilitate stocktaking and efficient policy making. The discussion not only involves indicators and measures, but also supporting infrastructures and technological solutions. A growing number of projects, including OPUS, GraspOS, and PathOS, as well as policy initiatives like CoARA, are actively addressing reforming research assessment to incentivise and reward Open Science. These efforts involve the establishment of observatories and the alignment of national and institutional policies, while also considering supporting infrastructures and technological solutions. The speakers explain the activities of different projects and initiatives, debating with the audience on the challenges and opportunities of aligning policies and practices developing a new research assessment system to incentivise and reward Open Science. In conclusion, the workshop provides an overview of the current state of Open Science practices in research monitoring and assessment. It will highlight the importance of monitoring the uptake of Open Science and of promoting Open Science practices to enhance the effectiveness of research assessment and lead to better research outcomes.