This thesis looks at the complex interaction between worker mobility and social policy in the EU framework. It aims to provide a comprehensive analysis of the policies and mechanisms that govern worker mobility and social policy, assess the impact of one on the other, explore existing challenges and understand the policy responses associated with worker mobility and social policy. The link between worker mobility and social policy in the EU represents a complex terrain shaped by competing interests, divergent national priorities and constantly changing socio-economic dynamics. As the EU strives to navigate this terrain, it must remain committed to the principles of solidarity, equality and social cohesion.