What is meant by a United States of Africa, and where does the idea come from? Is it feasible? Or even desirable as a realistic goal for the continent's diverse people? This paper traces the roots of the Pan-Africanist vision for the Organisation of African Unity (OAU), and then examines the prospects for its revival in the African Union (AU). It is evident from an analysis of OAU decisions, declarations and speeches over the years that Pan-Africanism was subsumed by African nationalism. It was a minority voice, seldom heard and at times drowned out by African nationalism. The ideals of founding fathers Nkrumah, Selassie and Nyerere did not have the support of the majority of African leaders, who were all concerned to a greater or lesser degree with the consolidation of state power. From the ideas and actions of a few visionaries, support for an African regional peacekeeping capacity and for human rights monitoring across borders grew into the AU institutions of the Peace and Security Council and the African Commission (and court) of Human and Peoples' Rights. The agenda for a United States of Africa goes further than what member states agreed upon in the AU Constitutive Act, however. The paper analyses the AU Commission's 'Study on an African Union government towards the United States of Africa' - a discussion document issued by the office of the chairperson of the AU Commission.