Walter Kasper is a leading German theologian and churchman of the post-Vatican II era who has written major volumes on Christology (Jesus the Christ) and Trinitarian theology (The God of Jesus Christ) and numerous volumes relating to ecclesiological and ecumenical concerns. While his work has been somewhat overshadowed by people such as Rahner, Balthasar, and Ratzinger, it is experiencing something of a revival under the present pontificate. In this work, The Catholic Church: Nature, Reality, and Mission, Kasper leaves us with his considered and scholarly account of ecclesiology. As with Kasper's previous major volumes on Christology and Trinity, the word that most accurately captures this present volume is magisterial. The work begins with a very personal chapter concerning Kasper's own ecclesiological journey from his theological formation, his major influences as a theologian, and the experience of Vatican II to his becoming a bishop and cardinal as secretary and eventual head of the Pontifical Council for Promoting Christian Unity. Most significant here is what he identifies as the “breakthrough” moment in his ecclesiological approach, the 1985 Synod of Bishops and the centrality of the notion of communio that emerged in that synod (20–23). This insight was further deepened by his work in the Vatican over many years of ecumenical dialogue and sharing. This is a work that resists easy summary. In chapter 2 it launches into the more familiar theological forms, presenting more than 300 pages (in small print) of rich and detailed theological argument (an additional 100 pages of footnotes) drawing together a relatively comprehensive set of ecclesiological themes. These locate the church within the context of salvation history and Jesus' preaching of the kingdom; he goes on in chapter 3 to explore different representations of the church: as people of God, as body and bride of Christ, as temple of the Holy Spirit, and Mary as archetype of the church. Chapter 4 explores the marks of the church as one, holy, catholic, and apostolic and the various tensions associated with each of these marks, such as the disunity resulting from the Reformation, the scandals that call into question the church's claim to holiness, the problem of denominationalism, and so on. Chapter 5 takes up the question of the internal structure of the church as the concrete form of the church's communio. This chapter contains much rich historical material, of the sort Kasper specializes in, illustrative of his theological position. Of particular value, to my mind, are the sections on office in the church, the development of episcopal, presbyteral and petrine ministry, celibacy, the question of women's ordination, and the recognition of ministry in other ecclesial communities. The final substantive chapter, chapter 6, deals with the missionary nature of the church, bringing together the notions of mission and dialogue. Kasper structures this as dialogue with various partners: dialogue with Judaism, a topic of special interest to him in his work in the Pontifical Council for Promoting Christian Unity ecumenical dialogue; interfaith dialogue; and dialogue with the world. Chapter 7, the concluding chapter, is much briefer, looking at the future issues that the church faces. For all the richness that the work offers its readers, it is not without difficulties and problems. I think the work is best placed in what Lonergan might call the functional specialty of doctrines rather than systematics; Kasper himself refers to the “dogmatic character of ecclesiology” (47). To my mind the volume lacks a clear systematic. For example, Kasper presents his account of ministry prior to his account of the church's mission. Yet if the church is essentially missionary by its very nature, and exists not for itself but for its mission (289), then the structure of ministry should arise from its mission. The account of the marks of the church, while a traditional dogmatic theme, occurs without an explanatory framework from which they might arise. Significantly there is virtually no discussion of the role of the social sciences in ecclesiology, just a few oblique remarks. Tellingly in this regard I found no mention of the leading US ecclesiologist Joseph Komonchak in Kasper's opus, nor of the work of more contemporary ecclesiologists. In places this gives the work a dated feel, drawing on scholarship that in some cases has been superseded, particularly his account of the meaning of diakonia (219), which ignores the work of Australian biblical scholar John N. Collins. There are also some technical problems with the volume's production, some incomplete sentences, misplaced text, some repetition, and oddities of translation. One such translation did bring a smile. At one point (279) the text refers to the church not wanting to become a “holy rest”; not a reference to some Sabbath observance, but to a “holy remnant” in more common theological language.