This chapter uses the concept of ‘informal international practices’ (IIPs) to explore the relational nature and origins of the African Peace and Security Architecture. It argues that ‘outinsiders’, actors who have one foot outside the door of public offices and the other foot inside official circles, have used IIPs to develop the specific elements of APSA and to get the leadership of the African Union, in particular African Heads of State and Government, to accept them as the main African peace and security framework. More specifically, the chapter describes how, on the one hand, African leaders have found appeal in and helped to shape a collectivist trait of the informal relational order underlying APSA. On the other, it analyses how outinsiders have used informal channels to introduce, adapt and consolidate specific norms and procedures. The chapter argues that, although tensions sometimes have existed (and continue to do so) between the primary objectives of the two groups of actors, the results have been narratives, policies, and practices that while influenced by larger, global discourses clearly reflect African agency with an impact on discourses beyond the continent. The chapter therefore offers a telling example of the importance of informality in international affairs.