This PhD thesis consists of three chapters in the field of empirical labour economics with a special focus on gender differences. The first chapter evaluates a weakly-enforced Swiss policy and demonstrates its effect in reducing the unexplained gender wage gap in Switzerland. The second chapter quantifies the impact of literacy and numeracy skills and their joint effect on wages in OECD countries, targeting particularly gender differences. The third chapter investigates how the choice of task-categorization methods influences job polarization patterns and points out the relevance of this choice by using the Swiss Labour Force Survey.