The Gender Equality Index was developed at the European Institute for Gender Equality to monitor the progress in gender mainstreaming within EU policy areas. This chapter outlines the political, conceptual and technical background in its development. It also positions it within the wider context of the 1995 UN Beijing Conference, and the ensuing release of international measure of gender equality, as well as its interaction with the global measures of inequalities within the Sustainable Development agenda. It then discuss further the structure of the Gender Equality Index, its six domains (work, money, knowledge, time, power and health) and satellites (violence, intersecting inequalities), and the indicators used. We offer a criticism of methodological updates,
arguing that recent ‘tinkering’ is at odds with the aim to offer a measure of gender mainstreaming. Finally, we conclude with examples of applications, an assessment of strengths and weaknesses, as well as some suggestions for future use.