The adoption of the Constitutive Act of the African Union marked a historic moment in institution-building and the continuing “move to institutions” in Africa. The African Union can be understood, at least, at two levels: first, as a manifestation of Africa ‘s collective response to the twin-challenges of globalism/globalisation and regionalism/regional integration; secondly, as an expression of a resurgent commitment to the ideology of Pan-Africanism and the enduring quest for deeper African unity. This essay examines the politico-legal context behind the move from the Organisation of African Unity to the African Union. It argues that the establishment of the African Union is not merely the most recent attempt at continental institutional reform and institution building, but that it also represents a unique constitutional moment which has provided African states with the opportunity for fashioning a new body of normative principles to guide their interaction and cooperation. While offering no comprehensive examination of all the core provisions of the Constitutive Act, particular attention has been paid to some key principles. Chief among these is Article 4(h), relating to the right of intervention, which potentially constitutes both a significant and controversial African contribution to the mapping of new international law. Overall, it is argued that the new organisation represents a radical departure from the political, legal, and institutional framework of its predecessor, and that it is founded on a range of new normative principles reflecting a changed attitude and a new approach among African states to the management of their common interests and challenges. The essay concludes by suggesting that the move to the new institution and the adoption of new normative principles will only have qualitative meaning when AU member states move beyond the mere exhortation and expression of lofty principles and ensure their effective incorporation in praxis.