A growing proportion of armed conflicts nowadays do not only involve political and ideological agendas but criminal ones. While armed conflict mediators have extensive experience of dealing with armed groups in various contexts of political and ideological conflicts, there is often a lack of attention towards addressing criminal agendas, making it a blind spot of mediation. In Strengthening mediation to deal with criminal agendas, James Cockayne takes an in-depth look at ways in which mediators have addressed, or not, criminal agendas, in peace processes, and the potentially spoiling effect that ignoring them may have had on those processes. Through the review of several peace processes in which criminal agendas have been directly tackled including gang truces in El Salvador and community violence reduction cases in Haïti and Brazil, Cockayne highlights how the practice of mediation can adjust to take criminal agendas into account. While mediation is by no means the only way to address and deal with such agendas, it can be a useful and complementary tool to do so. Cockayne also puts forward examples of peace processes in which criminal agendas were not taken into account and how this has contributed to spoiling those processes, for example through a return to conflict, or the empowerment of criminal agendas through disarmament, demobilisation, and reintegration processes. Cockayne also offers recommendations on ways to ensure that the fundamentals of mediation, such as preparedness, inclusive ownership, legal frameworks and impartiality, are respected despite the presence of criminal agendas.