In the past years, the number of mobile EU citizens has steadily increased. While free movement is at the core of European integration, mobile EU citizens face an increased risk of “falling through the cracks” of social security systems, hindering access to their rights and entitlements. The aim of this Thematic Fund is to improve EU mobile citizens´ access to rights by identifying barriers, and by promoting changes at the level of policies and practices, in various interconnected areas such as healthcare, homelessness, access to benefits, and entry and residence rights.