Thomas Kieselbach 1 Object and organisation of the study The present volume contains the first results of an international research project on youth unemployment and social exclusion describing the most up-to-date research of youth unemployment and health in six European countries. The project "Youth Unem ployment and Social Exclusion: Objective Dimensions, Subjective Experiences, and In novative Institutional Responses in Six European Countries" (YUSEDER) is supported by the Research Directorate General of the European Commission (DG XII) within the Targeted Socio-Economic Research Programme (TSER) of the 4th Framework Pro gramme. The YUSEDER research project tries to answer some crucial questions with regard to the risk of social exclusion associated with long-term youth unemployment. The European Commission launched a call for proposals looking for new know ledge of the key mechanisms linking the experience of long-term youth unemployment to various dimensions of social disintegration, conceived of in the theoretical frame work of social exclusion. In this context, not only the mechanisms exacerbating the stress of unemployment (vulnerability factors) but also the protective mechanisms pre venting or reducing the risk of social exclusion have to be taken into consideration. The second research question relates to new options of institutional and political inter vention and counteraction in different national contexts. These analyses will be underta ken in three Northern European countries (Sweden, Belgium, Germany) and three Sou thern European countries (Spain, Italy, Greece).