The term fallow is borrowed from agriculture as a metaphor to critically examine the role of strategic dormancy in cycles of valorization and devalorization of the built and unbuilt environment. Rather than a strict binary of fecund or barren, however, New Geographies #10 conceives of fallowness as a rich and complex terrain to provoke a critical examination of the sites, strategies, scales, and imaginaries of the unused, the devalued, and the dormant, and explore modes of revalorization in all its forms: economic, ecological, social, cultural. Ultimately, it is hoped that this compilation will provide a foundation on which designers can build new lines of questioning regarding processes of urbanization that will illuminate new speculative horizons for the design disciplines, while also demarcating points for cross-disciplinary study of the built and unbuilt environments. Co-published with Harvard University Graduate School of Design.