Parental leave policies have been shown to play a significant role in enhancing gender equality. The European Union has recognised this and has issued a Directive to its Member States, in order to instigate parental leave policy reform. However, not all Member States have sought to implement this. This thesis addresses this problem and seeks to answer the following research question: Why have progressive parental leave policies failed to transfer across the European Union? In doing so, this study also aims to explore the limits of Europeanisation. The research question has been addressed through a qualitative comparative case study of four European Union Member States: Sweden, Denmark, Hungary and Greece. These states have been chosen on the basis of Most Different System Design. The thesis deploys a theoretical framework based upon concepts of Europeanisation and policy mobility and draws particularly on the work of Stone’s four core concepts of policy mobility: Diffusion, Transfer, Convergence, Translation (Stone, 2012). The key factors that have been identified in this study as restricting the potential of a policy to transfer are: institutional surroundings, shared beliefs and norms, internal political dynamics and a lack of force/action from the European Union. These differences have acted to constrain the transferability of progressive parental leave policy across the European Union and therefore the process of Europeanisation in this area.