This multidisciplinary volume aims to shed new light on the variety of European uses of a political buzzword, solidarity. Growing out of the historically complex roots of religion, politics and knowledge, solidarity has developed a number of meanings that are all but straightforward. Is solidarity what holds the group from inside, or is it what the group displays towards those whom it represents? Is it a political project or a social condition? And is it a matter of faith or a rational option in a secular world? The passage of the concept into the discourse of the emerging ’global’ movements, as well as its adoption by official post-national discourses, has mirrored and magnified these uneasy questions. In particular at the European level, the answers to these questions have taken so different forms that it is tempting to see in them the expression of multiple solidarities rather than of one, common, as it were, solidarity. Setting as their common aim to shed more light on the ambivalent aspects of European solidarity, the chapters of this book are written by a number of renowned scholars, including Claus Offe, Peter Wagner and William Outhwaite.