Cross-border child relocation cases are among the most difficult disputes that family judges need to face. Commentators across the globe disagree on the interpretation of the child's best interests and the relevance of adults' autonomy in this context. As relocations are directly concerned with free movement, the literature has expressed an interest also in the European Union's influences in this area. However, considering its lack of competence in family law and the limited jurisprudence of the Court of Justice of the European Union on such issues, some questions about the scope and nature of obligations imposed by EU law remain open.  This thesis investigates, therefore, the following question: What is the (nature of) EU law's influence on cross-border child relocation and what are its effects on national legal systems? Its contribution is two-fold. Methodologically, it proposes a constructively oriented investigation of European influences in child relocation law. Cross-border movement constitutes the main raison d'être of EU law, and a defining feature of its community. Hence, a mixture of traditional values and new ways of life - sanctioned by a supranational entity - might lead to new dilemmas regarding children's interests and adult autonomy and complicate relocation decisions. The suggested approach allows contextual influences to be analysed together with legal doctrines, at both the EU and the national level. Substantively, the thesis builds on existing research to refine the understanding of child relocation in the context of supranational fundamental rights and freedoms in the EU, in their doctrinal and ideational dimensions. Finally, using case law from Germany, Poland, and England and Wales, it qualitatively investigates how national judges encounter the EU and draw from its ideational and legal features. This thesis demonstrates how the normatively inflicted EU context is occasionally used in courts but does not seem to consistently reorient national approaches towards the EU.