Present book aims at explaining the general principles and detailed rules governing public procurement at WTO and EU level to be applied by the respective national authorities. Thus, the first part addresses the multi­­­­­lateral GATS and the plurilateral Government Procurement Agreement, while the second part covers primary legislation of the EU and the Services Directive 2006/123/EC, the third part shows the provisions of Directives 2004/17/EC, 2004/18/EC, 2009/81/EC as well as the relevant rules on green procurement and the State Aid related rules on sales of land and buildings. With a comparative approach, those agreements of the EU with Third States of relevance in the field of public procurement are summarised, also considering the agreements of the EFTA and pro­­­­­viding an overview of clauses in other agreements between WTO Mem­­­­bers. Throughout the text, the new legislative proposals as published on 20.12.2011 and discussed since then, expected to enter into effect in 2014, have been integrated. The book reproduces the legal status as of 01.05.2013.