The Organization of African Unity (OAU), founded in 1963 and later transformed into the African Union (AU), plays a pivotal role in promoting peace and security across the African continent. The thesis highlights the AU's main successes in these areas, including the challenges faced and the countermeasures undertaken. A special emphasis is placed on the mediation in the Tigray conflict in Ethiopia, examining also the role of the Inter-Governmental Authority on Development (IGAD). The text provides historical context, starting from the OAU's inception and the subsequent membership of African states in the UN. It discusses the evolution of the AU, especially its efforts in peace and security, and introduces key organizations and initiatives such as the Peace & Security Council (PSC) and Agenda 2063.