The African Peace and Security Architecture (APSA) of the African Union (AU) is facing an uncertain future: Traditional security threats in Africa are intensifying and new challenges arise. At the same time, the external environment is changing rapidly, an unprecedented crisis of multilateralism is evolving while new state and non-state actors have appeared on the stage. In this context, the reform process of the AU and especially of APSA is of strategic importance for Africa to safeguard peace and the security on the continent in the long run. Against this background, crucial questions to the functioning of APSA need to be answered: How to adapt APSA to new security threats? Which actors need to be involved in decision-making and implementation? How to increase the cooperation and coordination between regional, continental, and global bodies in the field of peace and security? To tackle these questions, 35 leading African decision-makers, practitioners, academics, and civil society representatives designed four distinctive scenarios of the APSA in 2040 to explore alternative futures for collective security in Africa. This process is highlighting policy implications of decisions taken today and their consequences in the years to come.