This collection of essays will be found unusually interesting to church historians. It is the fallout from an ‘expert seminar’ at Leuven in 2007 ‘on the theme of the church Fathers and [modern] Catholic social thought’, itself part of a publicly funded (generous Belgium!) research project on the same theme. Predictably and confessedly the seminar, and the whole project with it, failed if to succeed is to produce clear evidence of the relevance of patristic social thought to the modern world. The seminar was agreed that all potential relevance must be indirect; selective quotation without context or substantial and historical explanatory glossing, of the sort official documents too often contain, being useless. Despite, and because of, this general recognition eleven papers, all good and realistic, some excellent with none entirely negative, were produced and are presented here in revised form with editorial introduction. ‘Catholic’ is understood with unaggressive latitude and is reinterpreted in the book's subtitle as ‘Christian’; ‘church Fathers’ means here Christian writers mostly of the first four centuries; ‘social thought’ means the practical application of the official teaching of the Roman Catholic Church in papal encyclicals and other normative texts (semi-official collections of these are named and are referred to). ‘Approaches’, ‘Contexts’, ‘Particular issues’ and ‘General reflections’ are the four classes in which the essays are ranged. Reimond Bieringer suggests ways in which the hermeneutical theories of Gadamer and Ricoeur can assist interpretation; Pauline Allen indicates and underlines its difficulties and pitfalls. Peter Van Nuffelin asks, in effect, what new understanding Christianity brought to socio-ethical thought and finds some but not as much as you might suppose; Helen Rhee stresses the importance of hopes of heaven for social ethics; Wendy Mayer considers the special case of John Chrysostom's audience notably when he illustrated Christian teaching from the visible example of the suppliant Eutropius (I would add that people at the time apparently thought it in execrable taste). Susan Holman writes on the notion of ‘the common good’, prominent in contemporary teaching and having a counterpart in the ancient; Brenda Llewellyn Ibssen on usury draws essentially the same conclusion as did Bingham but with valuable up-to-date references; Brian Matz studies Basil on spiritual detachment in its relevance to possessions; Thomas Hughson explores Lactantius and finds a fruitful, perhaps original, approach to social justice. Richard Schenk and a duo of editors ponder the conclusions of the whole project with mixed dissatisfaction and expectation. What emerges for me is the paradoxical importance of irrelevance, a point I find implied in a number of the papers and by the editors. The student of this period of Christian life and thought is given a salutary shock first by its strangeness and then, if sensitive to the Christian religion, by its familiarity. All potential relevance to the present-day world lies in the resolution of the two experiences.