This report maps the European landscape of Civil Society Organizations engaged in Horizon 2020 and Horizon Europe’s security research. It introduces a comprehensive dataset of CSOs participating in Horizon 2020 and Horizon Europe security projects and an initial categorization of their contribution across TRANSCEND’s four pilot domains: fighting terrorism and crime, cyber security, disaster resilient societies, and border management. Additionally, the report provides a curated dataset of all security projects in those framework programmes and a categorization across the project’s pilot domains, as well as an analysis of other types of actors involved in security research: key security research policymakers, impact assessment organisations, security practitioners (including pan-European network of practitioners), and research community experts. This mapping exercise, as well as the analysis provided, enables an identification of potential partners in civil society, contributes to different TRANSCEND tasks, and engages with some lessons learned from previous research. The document concludes with a set of best practices of civil society engagement with security research. The report advances the state of the art by providing a mapping of civil society engagement with security research and by opening avenues for future research, within and beyond the TRANSCEND project.