Social housing is an important dimension of social welfare policy and affordable housing provision, but there are significant differences across countries in the definition, size, scope, target population and type of provider of social housing. The relative size of the social housing sector has been shrinking in recent years in all but six countries for which data are available. At the same time, many countries have undertaken major building-revitalisation projects to improve the quality of social dwellings and the surrounding neighbourhoods. The COVID-19 pandemic has brought to the fore the enduring housing affordability and quality gaps facing many households.