One of the fundamental changes that have come about with the transformation of thernOrganization of African Unity into the African Union is the establishment of a comprehensivernpeace and security regime. The African Peace and Security Architecture is institutionalizedrnwithin the framework of the AU Constitutive Act and the Protocol on the Peace and SecurityrnCouncil.rnAPSA is a key mechanism for implementing the AU’s vision of promoting peace, security andrnstability in the continent. The African Union regards Africa’s sub regional organizations as anrnintegral part of its peace and security framework and building blocks of the African Peace andrnSecurity Architecture. Therefore the coordination and harmonization of the African Union Peacernand Security Council with sub regional organizations is significant. To strengthen this relation arnMemorandum of Understanding on Cooperation in the area of peace and security was signedrnbetween them.rnThe study seeks to describe and analyze the relationship of the African Peace and SecurityrnCouncil with sub regional organizations. To this end the paper first discuss the global peace andrnSecurity Architecture and then the Regional peace and security structure. The structure and therninstitutional design of AU PSC will be dealt by further analyzing the provisions of thernConstitutive Act, the MOU and the Protocol on the Relation between the African Union and thernRegional Economic Communities. The paper examines the structures of selected RECs andrnstudies their involvement in the area of peace and security and the coordination with the AUrnPSC.rnFinally the paper analyses the prospects and the challenges on the working relationship betweenrnthe AU PSC and the RECs. The paper concludes with recommendation for better developing therninstitutional relationship between AU PSC and RECs in order to facilitate more lasting andrnsustainable peace and security in Africa