Even though housing is one of the most fundamental human needs and the lack of affordable housing is one of the biggest challenges that urban societies face, housing has occupied a relatively frail position within systems of welfare, at least when compared to other domains of social policy (social security, health, and education). While on a national level comparative studies of housing policies and outcomes have enabled us to identify and explain trends of divergence on varying levels and forms of state investment across different welfare regimes (Kemeny, 1995; Alves, 2017), on a local level studies that compare large cities that face similar problems and challenges (e.g. related to migration flows, capital flows, increase of inequality) have identified traces of convergence (Alves & Anderson, under consideration). In the field of spatial planning, the theoretical debate has been oriented towards disclosing the diversity of planning systems in terms of scope, dominant paradigms, assumptions and forms of intervention. The debate on the relationship between housing and spatial planning has focused upon how cultural contexts and historical traditions have interacted with external factors and international interdependencies, in which the Europeanization of spatial planning policies and practices has been relevant. Bearing in mind the benefits of interdisciplinary and comparative approaches in the fields of social policy, this paper aims to contribute to the advancement of theory in the fields of spatial planning and housing policy by comparing similarities and differences in legal and institutional terms, philosophies, policy goals, and instruments in the provision of affordable housing in Portugal, England, and Denmark.