In our paper we investigate the role of civil society organisations (CSOs) in the provision of services and in forming advocacy coalitions for illegalized migrants in Bern and Vienna. We analyse the variety of CSOs which actively challenge policies of exclusion at the urban level. We examine the political and social practices of CSOs in local welfare arrangements and their organizational structures, the way they build up solidarity relations, networks and alliances, and their relations to municipality and urban authorities. By focusing on varieties of practices and strategies of CSOs, we shed light on civil society’s crucial role concerning the construction of urban infrastructure of solidarity and aim to show how local arrangements for illegalized migrants are co-produced and negotiated by a variety of actors within urban settings.