Gaudium et spes (Pastoral Constitution on the Church in the Modern World) was promulgated on December 7, 1965. It mirrors a new spirit of openness of the Catholic Church to the world, as well as a new historical consciousness, based on a self-understanding of the Catholic Chuch as "linked with mankind and its history by the deepest bonds" (GS, 1). This historical consciousness resulted in a method of social discernment which, inspired by John XXIII, was articulated by Gaudium et spes in terms of 'scrutinizing the signs of the times' and of 'interpreting them in the light of the gospel' (GS, 4). Conscious of the need to revisit the pastoral constitution of Vatican II, the Centre for Catholic Social Thought at the Catholic University of Leuven, has organised two international expert seminars. The first expert seminar (6-7 September 2003) was rather explorative and focused on the relevance of catholic social thought in its actual context with special attention paid to the signs of the times in an era of globalisation.The discussion on the contemporary signs of the times revealed the necessity to clarify the theoretical and practical implications of the methodology of social discernment and particularly of a social hermeneutic in the light of the gospel. This became the theme of a second expert seminar (Leuven, Louvain-la-Neuve, 9-11 September 2004), the discussions of which are the background to this book.