Many states and cities worldwide have introduced densification policies over the past twenty years (Dembski et al., 2020, e.g., UK, Germany, Switzerland, U.S. cities). Densification aims to transform urban settlements with main goal to increase environmental sustainability (e.g., limiting land uptake, reducing need to travel by car). In dense cities, the implementation of densification mostly relies on the transformation of the existing old, and therefore affordable, housing stock, through urban upgrading and the replacement and renovation of buildings (Burton, 2000; Searle & Filion, 2011; Touati-Morel, 2015). Consequently, increasing numbers of residents are suffering from social eviction and displacement due to urban densification, modernization, rising rents, and intense housing commodification (Aalbers, 2017; Christophers, 2022). Vulnerable resident groups – such as older people, migrants, or households with children – can no longer afford to live in central locations, or experience unstable or insecure housing conditions (Lees & White, 2020; Kadi et al., 2022). A scenario that is highly unsustainable (Debrunner et al., 2022).

So far, studies on densification have mainly considered the process as technological, architectural, or design-based problem (e.g., Bibby et al., 2020; Broitman & Koomen, 2015; Kyttä et al., 2013). However, systematic knowledge on governance processes and their impact – regarding the integration of environmental and social sustainability goals – is still lacking. This Special Issue (SI) contributes to examining densification and urban transformations by analyzing densification from an actors-oriented and socio-political perspective. The point of departure is that densification per se does not necessarily lead to sustainable outcomes in terms of social inclusion, cohesion, or community stability – but instead it is often practiced as a 'Business' that is dominated by powerful, resource-rich, and technocratic actors. These governance arrangements tend to prioritize urban growth objectives (e.g., Logan & Molotch, 1987), and to exclude diverse and communityoriented voices (Madden & Marcuse, 2016; Scally & Tighe, 2022). The articles in this SI covering densification processes in diverse cities worldwide. They politicize this 'Business of Densification' by examining how the densification process is negotiated, governed, planned, and implemented by the different actors involved.