The current migration flows toward Europe are having a significant impact on social composition, economy, urban services, and on the physical dimensions of cities. Cities have a key role in developing immigration policies and sustainable accommodation models, that can promote an inclusive society as well as local development. Due to the persistence of migratory flows, these models of integration and development cannot be supported by an emergency condition, but they should be based on systematic strategies. This paper presents a series of accommodation models and urban policies, coming from international experimental projects, that we argue can foster integration and urban development. These strategies show the potentials of immigration in boosting urban transformation and regeneration. Innovative strategies for dealing with immigration are based on flexible tools, typically from temporary habitat (housing modules, light construction systems, customized solutions) that find a place inside the city. Integrated design strategies use the existing city as a frame being filled up by flexible houses, through urban densification or regeneration process. Housing dissemination, temporary and flexible architectural solutions and inclusive process are the drivers for developing a flexible habitat, at the base of a more sustainable and democratic city.