The thesis investigates the relevance and effectiveness of pay transparency in reducing the gender pay gap, focusing on the new European directive addressing it. Despite progress, the EU gender pay gap remained at 12.7% in 2021, driven by factors such as sectoral segregation and the "glass ceiling," while some disparities remain unexplained. To uncover these hidden factors, the directive imposes pay transparency obligations on employers, mandating salary disclosures and facilitating employee disputes. However, challenges persist, including inconsistent implementation across Member States and weak enforcement mechanisms. While pay transparency is a step forward, broader systemic changes are needed to achieve true gender pay equality.