Household debt has risen markedly since the turn of the century and stands at a historically high level in most OECD countries. This paper offers an overview of developments in household debt over the past decades across a large sample of OECD countries, highlighting both common trends and country specificities. It examines the vulnerabilities associated with high household debt for households, the financial system and the wider economy. Finally, it describes the challenges faced by policymakers at the current juncture and outlines responses in terms of monetary, micro and macro-prudential, and housing policies.