The achievement of gender pay equality has become a central topic on the policy agendas of many countries under the directive of the European Union. Nevertheless, pay differentials between work of equal value continue to be observed without significant evidence of improvement. Labour economists have taken a deep interest in the estimated gender pay gap and the identification of its causes. This book adds to this literature by providing new answers to explain this phenomenon. We use a panel of European countries and investigate the role of human capital, unobserved heterogeneity and wage structure on the gender pay at a specific moment in time and over time. It also investigates the causes of the pay gap beyond gender differences and takes a look at the penalty women face for having children and the role of family policies. Finally, it particularly analyses the situation of those mothers who are the most vulnerable on the labour market: single mothers. The analysis should help shed some more light on gender pay equality, and should be useful to academics and researchers working on gender issues, but also to policy makers and other stakeholders dealing with gender mainstreaming.