Much attention is given to the existence and measurement of gender inequality, but relatively little attention is given to the economic costs that result from the presence of inequality. This topic was the focus of our November 2016 conference at the Centre for European Policy Studies in Brussels. We invited a diverse group of speakers to discuss their research on the costs of inequality in the labour market and beyond. Published here are the conference papers of those proceedings. What is apparent is that while the quest for gender equality is a necessity in itself as a matter of justice and fairness, the existence – and persistence – of inequality has a significant effect on the economic performance of Europe.