Over the past 30 years, the UN Security Council has played an increasingly far-reaching role on questions of transitional justice, including with respect to serious human rights violations, accountability, institutional reform and conflict transformation. Despite decades of experience, however, the relationship between Security Council practice and impact in post-conflict transitional justice settings is poorly understood. As a result, there is little evidence to demonstrate whether particular Council approaches (language, tools, and other forms of engagement) are more effective than others. In response, the Swiss Government is supporting a project that aims to answer two related questions: How has Security Council language on transitional justice changed over time, and what impacts have Security Council approaches had in transitional justice settings?In addressing these questions, the project aims to understand both the evolution and the effectiveness of the Security Council’s approach to transitional justice, aiming to inform more impactful practice in the future. The findings of this project are therefore of direct interest and importance to the Security Council, Member States, transitional justice practitioners, and those engaged in post-conflict reconstruction and peacebuilding.