The term ‘affordable housing has been rapidly gaining currency over the last decade across Europe, both in policy and research circles. While it is often used as a synonym or close relative of the term ‘social housing, more recently it is finding its own definition and policy instruments in specific cities and countries. However, boundaries between both concepts remain unclear. To shed light on recent developments of each of these terms, this paper presents findings from a study commissioned by the European Investment Bank, which investigated current trends in definitions, programs and policies both in social housing and affordable housing. This paper focuses on findings for England, Italy, Poland and The Netherlands. Methods used included desk research and interviews with key informants in each of the four countries. In addition, in-depth information about Italy and The Netherlands was gathered through stakeholder workshops carried out between September and November 2016. Findings show that affordable housing in all four countries is becoming a more distinct field, in parallel to developments in social housing. In addition, the paper describes some innovative policies undertaken to develop affordable housing solutions. The paper concludes with a reflection on scenarios for future policy developments and an agenda for further research.