Employing international relations theory's concept of the new medievalism, this article applies a model of informal governance to the study of post-apartheid South Africa, arguing that what appear to be ungoverned spaces, criminality or corruption may in fact represent the development of informal governance. Employing a political-economy approach, it analyses the rise and decline of the modern state by reference to the relative efficiency of actors in the formal and informal systems. After an initial upsurge of neo-medievalism following the end of apartheid, the South African state has enjoyed recent success reasserting its sovereignty, although this may yet prove temporary.