Previous international tribunals demonstrate that the work of international criminal justice mechanisms (ICJMs) and local civil society organizations (CSOs) often overlap. However, this shared mission has not always led to close cooperation. Little formal guidance is available to guide ICJMs and CSOs on how best to work together to accomplish their shared goals, yet professionals working in the field offer a wealth of practical information. This report relies on 30 interviews with local CSO staff, former international criminal mechanism staff, and subject-matter experts to ascertain how past experiences can inform future frameworks for ICJM-CSO cooperation. This report was researched and written by Jennifer Keene in close collaboration with the Syria Justice and accountability Centre (SJAC).