The principle of free movement of workers within the European Union is of great importance to the functioning of the internal market. As a result, exceptions to the fundamental principles of the European Union are kept to a minimum and are interpreted narrowly. One of the exceptions to the free movement of workers is the so-called ‘public service’ exception, which is laid down in Article 39 (4) (ex Article 48 (4)) of the EC Treaty. The main object of this book is to analyse this exception, both at the European level and the national level. In the first part of the book the author analyses in detail, the case law of the European Court of Justice dealing with the correct interpretation of the public service exception. Attention is also paid to the concepts of nationality and (European) citizenship. National legislation dealing with nationality requirements for employment in the public service in the Netherlands, Belgium and the United Kingdom are explored in the second part of the book. The book also offers a more general comparison of nationality requirements as they can be found in a number of other EU Member States.