This book assesses the balancing act between EU free movement law, fundamental EU objectives and Member States' concerns regarding their welfare systems. It takes a novel dual approach: namely combining doctrinal analysis of EU citizenship case law with an examination of mobility data. This allows the study to clearly show an imbalance between the representation and protection of these conflicting interests in EU case law. It goes further, identifying avenues for reform and highlighting the importance of the principle of proportionality for attaining a legitimate balance of interests. In a field in which much has been written, this offers a truly original perspective. It will be much welcomed by scholars of EU free movement and citizenship law.