Book excerpt: This book investigates policies for the promotion of housing affordability in the rental sector of attractive cities in Europe. Affordability links the housing situation to the economic situation of households, referring to conditions of access to housing and to the role of housing in determining poverty or wealth. The book examines the current affordability crisis and frames it in the ongoing process of urban restructuring and devolution of welfare. From the perspective of the Foundational Economy, the book calls for a proactive and effective role of public administrations in making the rental sector an affordable and stable alternative to housing financialization and commodification. By intertwining theory construction and real-world data collected through case studies in Milan and Vienna, the book provides an original framework for the analysis of public policies that promote rental affordability in a multi-level setting. Through the analysis, it highlights critical nodes of the different (housing, urban, and social) policy domains at stake in the promotion of rental affordability in attractive cities. The book proposes a shift from the currently dominant supply-side argument to an integrated, intersectoral and multi-scalar policy system for making cities more affordable.