Ten years ago, the Bayerisches Landessozialgericht referred four questions to the Court of Justice for a preliminary ruling, the resulting judgment on Maria Martinez Sala’s entitlement to a child-raising allowance finally yanked the concept of Union citizenship from its sluggish hinterland in the EC Treaty and launched the Court and the Community legislature on a mission—to uncover the substantive content and scope of citizenship, and to realise its potential as an autonomous rights-giving force. The intervening decade has seen enthusiastic, if not always coherent, progression of this vocation, and thereby renewed animation of Community law on the free movement of persons. Much work in this field seeks to plot the evolving rights for EU citizens, but what about the position of the Member States? Their capacity to determine and manage their own immigration rules had already been eroded by ‘traditional’ Community law on workers, establishment and services.