Claudia Hupkau, Barbara Petrongolo Despite changes in social norms and policy reforms over recent decades, gaps in hourly wages between similarly qualified women and men remain significant, ranging between 10% and 20% in most OECD countries (OECD 2018). The ongoing COVID-19 crisis has made the issue of addressing gender wage gaps even more pressing, as most of the increased household responsibilities fall to women, which may further reduce their earnings in the long term (Fabrizio et al. 2020, Queisser et al. 2020, Sun and Russell 2021). In order to devise effective policies to narrow gender wage gaps, we first need to understand what their drivers are. In a new paper (Ciminelli et al. 2021), we source data on earnings, hours worked, and many other labour market and demographic characteristics for over 33 million individuals in 25 European countries to analyse the role of social norms and discrimination (‘sticky floors’) as well as the wage penalty related to childbirth (‘glass ceilings’).