Giovanni Sartori once described African party systems as "formless." Our contribution challenges this view in an era of resurgent multipartism that swept through the subcontinent in the early 1990s and continues until today. The article brings together contemporary research on African party systems with the wider disciplinary literature on party system institutionalization. Using a data set including all continuous election sequences in Africa from 1950 to 2008, we find that Africa has some of the most volatile party systems ever recorded and yet, tremendous diversity across regimes. We test the relative impact of political institutions, economic performance, the history of party system development, and social cleavage structure on party system institutionalization in Africa. We find that its party systems have been shaped by a set of factors unique to the subcontinent, but some of the general global patterns of party system development hold true in Africa as well.