Housing affordability presents a pressing global issue. While there is a growing need for more urban housing, implementation and regulation of housing densification is highly controversial, especially in Switzerland, where local referendums can delay urban development. The article examines residents’ acceptance of housing densification through a three-step research design, utilizing original experimental survey data and combining stated and experimental behavior with subgroup heterogeneity analysis from 3,497 residents across 162 Swiss cities and towns. Findings show acceptance of housing densification to be influenced by individuals’ relative housing costs, perceived neighborhood density, and political ideology; by social and ecological policy instruments; and between subgroups on socio-economic and ideological grounds. Ultimately, results highlight a broad coalition supporting densification to provide affordable housing and address ecological concerns, offering insights for policymakers. Studying residents’ opinions and behaviors within a direct democratic system and renters society further contributes to advancing theoretical understanding of housing politics.