Informal urbanism, from informal settlements to economies and street markets, is integral to cities of the global South - economically, socially, environmentally and aesthetically. This paper seeks to unfold and re-think this informal/formal conception using two interconnected theoretical frameworks. First is assemblage theory derived from the work of Deleuze and Guattari, in which a series of twofold concepts such as rhizomic/tree and smooth/striated resonate with the informal/formal construct. Second is theory on complex adaptive systems, in which dynamic and unpredictable patterns of self-organisation emerge with certain levels of resilience or vulnerability. These approaches are drawn together into the concept of a complex adaptive asse...