This introductory essay aims to provide a comprehensive overview of a collection of 17 articles, previously published in the Urban Studies journal, now consolidated as a ‘virtual special issue’. The articles contribute to numerous strands of what has, over the decades, become an extremely voluminous literature concerning the interplay between population change and productivity within cities. It is important to acknowledge that the volume of this literature makes it effectively impossible to summarise effectively in a single essay. This article instead presents a contextual overview, a glimpse into the various thematic strands arising from the literature, and an introduction to each of the selected virtual special issue articles themselves. It briefly highlights the unique contributions of these articles to the overarching objective of the Urban Studies journal, which is to advance our understanding of the urban condition. Yet, it is also worth noting that the literature does not neatly segregate into distinct strands. Indeed, several contributing authors within the virtual special issue rightly emphasise the significant interdependencies between population change, migration patterns, specialisation, firm location, urban and natural amenities, agglomeration economies, and productivity. This essay attempts to progress logically from one strand to another, with a specific focus on labour and housing markets, as well as transportation costs or systems, as mediators of these complex relationships. Finally, the essay concludes by bringing attention to several strands of future inquiry that might prove fruitful and would be of interest to the readership of this journal.