This book publishes the results of the NATAC project in two volumes. The acronym NATAC stands for ‘Acquisition of Nationality in EU Member States: Rules, Practices and Quantitative Developments’. NATAC was a Specific Targeted Research Project funded by the 6th EU Framework Programme. The project was limited to the fifteen Member States of the European Union before May 2004 and was carried out between September 2004 and November 2005. One problem we faced was that there is currently an increase in legislative activity in matters of nationality. Collection of data for systematic comparison had to be limited to the period from 1985 to the end of 2004. However, we have attempted to update the country reports published in Volume 2 by including information on legislative reforms up to February 2006. In all modesty we claim that these two volumes represent the most comprehensive comparative study on nationality in Europe so far. However, we are perfectly aware that there is more to be done. First, ongoing reform will quickly require updates for some of our data. Second, we have not fully explored all possibilities for further comparative analyses of our data. Since we want to make them useable by other researchers, we make available under www.imiscoe.org/natac more extensive versions of Chapters 2, 3, 4, 6 and 9, the various questionnaires answered by our country experts, excel sheets that provide a comparative overview on the modes of acquisition and loss of nationality in all countries as well as more detailed information on each country and national statistical data not included in the Chapter on statistics. Third, we also felt that a study like this should not be limited to the pre-2004 Member States of the EU, but ought to include the ten new members as well as Turkey as an accession candidate and the most important sending state for immigration in Europe. We therefore organised another workshop on this topic in summer 2005 through the IMISCOE network. (IMISCOE stands for ‘International Migration, Integration and Social Cohesion in Europe’ and is an EU-funded network of excellence in migration research, coordinated by IMES at the University of Amsterdam.) Revised papers from this workshop will be published separately in a third volume in the same series under the title ‘Citizenship Policies in the New Europe’. What we have not yet been able to do is including the new Member States and Turkey in the systematic comparative analysis presented in the present volume.