For some time now, »megacities« have been receiving focused attention from the media and academics. However it is unclear which qualitative specifics really go along with size. Johanna Hoerning critically ties this question in with classical sociological analyses and current debates alike. Her comparative investigation is based on a spatio-theoretical understanding of cities, which introduces the concept of fragmentation as an heuristic concept for urban analysis, but also connects these with structures and practices of the everyday experience of cities. In directing the empirical focus onto Brazil, it also expands the Euro-American framework of the academic production of knowledge.