Strategic use of land policy instruments for affordable housing – Coping with social challenges under scarce land conditions in Swiss cities

•The provision of affordable housing is to be regarded as a land policy issue.•Affordable housing provision results from the intertwined relationship between land use planning (public policy) and property rights – the two main sources of formal constraints.•Planners can influence the private property owners’ behavior in favor of increased housing affordability if they are able to find ways which reinforce their position in front of powerful landowners.•The mere availability of land policy instruments is not sufficient but the strategic activation of specific instruments matters for effective affordable housing provision. For decades, many cities have introduced densification policy objectives to stop urban sprawl or to promote efficient use of natural resources. In the urban housing sector, however, densification projects often intensify social challenges. Due to rising rents after modernization of existing housing stocks as a consequence of densification, low-income tenants are forced to leave their apartments. Risks of social exclusion and segregation increase simultaneously. In this article, we analyze how municipal planning authorities cope with affordable housing shortages in a context of urban densification. Specifically, we ask: How do municipal planning authorities promote affordable housing in densifying cities? To answer this research question, we apply a neoinstitutional analysis approach to better understand (1) the basic mechanisms of how land policy instruments impact affordability, and (2) why specific instruments are activated to defend affordable housing objectives. Through qualitative case study analysis of four Swiss urban municipalities, our results show that the mere availability of land policy instruments is not sufficient but that the strategic activation of specific instruments matters.