“Non-take-up”, which describes the situation of “anyone who – for whatever reason – does not benefit from a public offer of rights or services to which they may be entitled” (Warin, 2016a), is the subject of growing, shared interest in countries with widely varying social security systems. There is a tendency for social support systems to grow in complexity in order to adapt to the diverse range of situations they are designed to serve; situations which are becoming increasingly characterised by their instability. When people do not receive benefits to which they are entitled, the risk of poverty and exclusion increases, espe-cially when the benefits in question are intended for the poorest individuals. Although our understanding of this phenomenon and its causes has advanced thanks to the now abundant literature on the subject, measuring the extent to which it exists remains a major challenge: any such means of measurement must satisfy the social demand for statistics on the subject whilst also helping to refine our understanding of the mechanisms by which we can combat non-take-up. This DREES Report, written in collaboration with the Observatoire des non-recours aux droits et services (Odenore), aims to report on the efforts to quantify non-take-up of guaranteed minimum income in five European countries with different national social security systems, but also a shared, long-term interest in the issue of non-take-up. The study covers Germany, Belgium, Finland, the United Kingdom and the Netherlands. More specifically, this report aims to present the main non-take-up rates for minimum income in the countries studied as well as the methods and data sources used to evaluate these. It briefly describes the different social security systems, followed by the origins and context of the steps taken to quantify non-take-up in these countries. Finally, it attempts to identify the main actors and areas of data production. This stocktaking allows us to analyse whether certain types of data production have helped to put this phenomenon “on the agenda” and, if so, whether they have also helped to qualify it and define it as an issue. The study is based on material comprising a literature review and discussions and interviews with actors who produce data and/or possess expertise on the subject. Given the number of works quantifying non-take-up, the period covered by the study primarily covers those produced within the past ten years.