On 19 June 2011, the deadline for the implementation of Directive 2009/50/EU on the Conditions of Entry and Residence of Third-country Nationals for the Purposes of Highly Qualified Employment expired. In its first part, this book highlights the decision making of the Blue Card Directive and the principles of its legal system and puts the directive into an international perspective. In its second part, the book shows the impact of the directive on the national level by an analysis of the transposition in five Member States. The contributions are based on lectures presented on a seminar on the Blue Card Directive, organised late 2011 by the Centre for Migration Law, co-sponsored by the Jean Monnet Programme.We decided to publish this book on the results of the seminar, thus enabling those who could not attend to benefit from the wealth of knowledge and information which was shared during the seminar. At the time of the seminar the transposition in some Member States was still pending. However, the authors managed to insert relevant developments which took place in 2012, in their contributions to this book.Tineke Strik & Carolus Grütters