Through the creation of an original theoretical framework, this paper demonstrates the value of a deeper engagement between autonomist Marxism and (urban) geography. By spatialising arguably the autonomists’ key theoretical contribution – class composition – the paper develops the ideas of technical and political spatial compositions. These dialectically intertwined concepts provide a framework with which to analyse the relationships between shifting urban spaces and struggles, and clarity is therefore added to another key autonomist concept, the evocative yet nebulous ‘social factory’. Applying these to Buenos Aires, the paper focuses on various spatial conjunctures, exploring their emergence and the immanent potentials for radical spatial politics they afford and preclude. In particular, the paper provides a detailed reading of the complex role Buenos Aires’ ‘informal’ settlements play in both perpetuating and resisting a neoliberal, financially extractive economy. The benefit of a ‘spatial composition’ framework is twofold: it provides a periodising heuristic with which to originally and usefully approach urban struggles, and, in unpacking the ‘social factory’, it can be applied widely as a form of radical geographical praxis. The paper thus makes important theoretical and empirical contributions to an exciting, emerging autonomist (urban) geography, as well as to studies of Buenos Aires.