There has been little comparative research on the differences across radical social movements in the context of consolidated democracies. This paper analyses the squatting movement, as an exemplary case of contemporary radical movement. This study aims to identify the causal contexts that explain the differences of strengths within these movements across 52 large cities in Western Europe. It examines three main hypotheses drawn from the literature on social movements concerning the characteristics of political systems, the availability of resources and the presence of economic grievances. We use fuzzy sets qualitative comparative analysis (fsQCA) to identify configurations of causal conditions. The findings show that diverse contexts (multi-causation) lead to strong movements. A first causal context combines grievances, resources and closed or unresponsive institutions, and is typically found in Southern European cities. A second context highlights the presence of robust far-right parties in combination with less severe grievances and relative scarcity of resources, and is typically found in Northern European cities. These findings demonstrate that resources and grievances are quasi-necessary conditions for strong radical movements, although polarization can lead to a similar outcome where these characteristics are not present
