The rise of temporary urbanism has undoubtedly become a defining feature of the past decade in architecture, artistic practices and urban policy circles, above and beyond responses to vacant and empty spaces. From theatres and community projects to green spaces, shops and art galleries, the ‘pop-up’ adjective has come to embody a normalisation of the temporary as an imaginary of urban inhabitation and urban experience. Performative, transformative, cosmetic: understanding this strand of urbanism requires a thick and situated account of its contested emergence and of the unresolved tensions that continue to inform contemporary urban practice after the pop-up. In this book I have presented contested, multiple, entangled and situated stories about the emergence of temporary urbanism and its development in post-2008 ‘austerity’ London. Through in-depth semi-ethnographic accounts of different places, urban practices and their narratives, I have examined the establishment of the seductive ideal of the temporary city: an urban model that glorifies ephemerality and disruption over continuity and permanence. The ideal was nourished by multiple and divergent cultural genealogies and longer histories of alternative artistic and architectural practices, which have too easily associated vacant spaces and temporariness with the imagined ‘interstices’ of the city. I have called this construct the ‘alterity trope’ of temporary urban practices. To explore this trope as a field of position-taking, I have drawn on situated accounts of ten years of pop-up and temporary practices in London and made the case for the need for a longitudinal analysis of narratives and counter-narratives, policies and performative practices.