In recent decades, cities and territories have radically changed; the ecological, societal and technological transition has opened up an entirely new season of thinking in the field of urbanism, entailing a necessary and deep revision of tools, categories and methods inherited from the past. The variety of spatial forms that articulate infrastructures, built morphologies, bio-environmental systems, economies, and urban-rural relations, challenges simplistic oppositions such as centre/periphery, city/countryside, nature/society and call for new alliances among disciplines. Climate change, the depletion of energy resources, growing migrations, the emergence of new forms of work and lifestyles, or the rising impact of digital technologies, are just some of the dynamics that are thoroughly transforming the ways in which our urbanized territories are rapidly developing and which upcoming generations of architects and urbanists will have to increasingly deal with. The issues of the contemporary architectural and urban project related to environmental and social equity/security, require a deep rethinking of technical knowledge and embedded traditions, and this beyond any principle of hierarchy or historical progress. As much in scientific – experimental and theoretical – as in professional practices, Comparison seems more essential than ever. Scientific training in comparative methods requires regular updating, in order to take into account, on the one hand, the rapid evolution of socio-spatial realities under study, methods of data collection, and archiving, and on the other, the variety of languages, techniques, and scales involved in the description and analysis. Comparing Habitats aims to discuss the actuality and the problems related to Comparison as a Scientific Method and its heuristic efficiency, while focusing on its devices, purposes and challenges.