The paper of Katarina Hyltén-Cavallius focuses on personal identity numbers in Sweden and Denmark. This paper looks into formal and informal structures, which organise society in a host member state and which can make it difficult for a non-national Union citizen to, in practice, access public and private services on equal terms with resident nationals. It appears that although a personal identity number is of significant practical importance for residing in and taking part of society in Sweden and Denmark, the fact that the possession of a personal identity number is widely required by both public and private organisations, leads to indirect discrimination on grounds of nationality, which is incompatible with the key principle of non-discrimination underlying the free movement of persons, and thus a restriction on the exercise of freedom of movement.