Transnational social movement studies have long neglected the way activists from the South, and particularly from Africa, have participated in World Social Forum processes. Alterglobal activists have also been accused of neglecting or dominating southern voices. The organization of the WSF in Nairobi was seen as an opportunity to make African voices be heard. This examines how Africans activists participated in Nairobi, and the complex relationship they have to northern and other southern (such as Asia and Latin America) activists. The African alterglobal movement is seen as a space of tensions (i.e. between South Africans and the rest of the continent, between French and English speaking Africa, or between NGOs and more radical organizations) reflected in national mobilizations. Our team of 23 French and 12 Kenyan scholars made collective ethnographic observations in more than a hundred workshops and conducted 150 biographical interviews of African activists in order to examine how: Africa was referred to in the WSF; activists financed their trip to Nairobi; and Afrocentric, anti-imperialist, and anticolonial arguments have been used.