There is a growing interest in the issue of squatting vacant buildings due to the economic crisis and the reactions to foreclosures. Up to date most research focuses on the squatters’ agency and the legal conflicts associated to trespassing. However, a joint analysis of political, historical, urban and social contexts of squatting is still missing. In this paper I adopt the perspective of protest cycles and socio-spatial structures to illuminate how urban political squatting evolves according to significant contexts. The empirical evidence that supports this approach stems from the city of Madrid. I examine all the cases of squatted “social centres” from 1977 to 2016 by determining the dimensions that help interpreting their urban impact. Instead of viewing the development of squatting as a mechanistic reaction to housing shortages, high vacancy rates and urban speculation I argue that (1) the squatters’ movement was configured in tight articulation with other social movements, (2) critically responded to various urban and political dynamics, and (3) was able to self-reproduce itself by making use of specific opportunities in each period while keeping some crucial and long lasting strongholds.