Regional and sub-regional organisations in Africa play vital roles in the promotion of peace and security on the continent. The African Peace and Security Architecture (APSA) mandates certain roles for AU-recognised Regional Economic Communities (RECs), and RECs have been active in many peace and security spheres from early warning to peace missions. This article seeks to illuminate the changing landscape of regional security governance in Africa, primarily through the lens of formal peace agreements, which are important tools for ending violent conflict. Extant research does not establish the frequency and capacity of regional organisations’ engagement in peace agreements. We present original quantitative data, systematically tracing these evolving and uneven activities. Our data establishes trends of REC peace agreement engagement that vary across Africa’s sub-regions during 2002–2015. We further explore patterns of organisational interaction, presenting case studies of peace processes that highlight important variation in terms of the distribution of influence and authority.