With her monograph on leadership in the thought and activity of Gregory the Great, Müller makes a valuable contribution to the study of Pope Gregory i (590–604), whose pontificate has long been recognised as pivotal in the history of the Church and papacy, even of western Europe. Müller adopts a chronological approach to Gregory's works, which include here his correspondence. This has certain advantages. Among these is the opportunity to set Gregory's various works in their individual historical context, from the time of his entry into the monastic life during the 570s in respect of his (fragmentary) Expositio in Canticis Canticorum, to the dawn of the seventh century with the Libellus responsionum and Gregory's final letters. What emerges is a considered and insightful analysis of Gregory's development as a thinker and practitioner on a range of matters linked to the theme of leadership, including the ecclesiastical hierarchy and the mission of the Church. The theme itself is well chosen since, as Müller points out, Gregory spent most of his life in assorted positions of leadership and reflected constantly upon the duties incumbent upon (especially) the Christian bishop as a leader of God's people. Of course, an important part of that reflection is summed up in Gregory's Regula pastoralis, but Müller does not allow that work, composed shortly after Gregory's election as bishop of Rome in 590, to dominate her account. Far from presenting the Regula as the ‘last word’ on Gregory's views on leadership, Müller demonstrates that Gregory's thought continued to evolve, not least under the many pressures of bearing papal office itself. As such, both the Homilies on the Gospels and the Homilies on Ezekiel can be appreciated as meaningful milestones in Gregory's intellectual evolution. This is a significant achievement since, as Müller herself writes, Gregorian studies (‘allzu lang auf Konsistenz bedacht’, p. 417) have traditionally struggled to free themselves of the temptation to impose a unitary view of their subject. With Robert Markus and Conrad Leyser's work in English and Sophia Boesch-Gajano's efforts in Italian, Müller is amply justified in claiming that, with her emphasis on the many-sidedness of Gregory's character and the significant ambivalence inherent in many aspects of his thought, the student of Gregory has received the latest addition to the most methodologically up-to-date work in the field (‘der neueste Strom vom Gregor-Studien’, p. 417). The Gregory that takes shape in Müller's account is more self-reflective, more subversive and perhaps, ultimately, more fragile than the ‘Consul of God’ we have come to expect. Rightly, Müller emphasises the importance of Gregory's life before his election as pope for a proper understanding of his character as a human being and his attitude towards the Christian life. A theme of particular importance, even at this early stage, is Gregory's view of the widespread failings of the institutional Church and its leaders, the bishops. In fact, Müller argues that Gregory continued to struggle his life long with the disjuncture he frequently perceived between the exceptionally high standard of personal holiness required of the Christian leader and the worldly pleasures and preoccupations either imposed upon or sought out by the episcopal leadership of an imperially sponsored Church. In this respect, Gregory's idealism is well known, although his considerable pragmatism, particularly during the period after 595, perhaps less so. Müller shows, for example, that, in his later years, Gregory was willing to concede that wily clerics, rather than contemplative ascetics, actually made for more effective bishops, a pragmatic view of the Church's role as a powerful social and political institution in Italy that was accompanied by an increasingly brittle assertion of the jurisdictional primacy of the bishop of Rome over the whole Church, including Constantinople and the east. Müller also makes a convincing case out of the discrepancy she sees between Gregory's high appreciation for the task of the praedicator and the top-down method of mission (rooted in the conversion of the ruler) he employed in his various missionary projects (which themselves must not be confined to Kent). Among criticisms that may be made of Müller's account, some readers will find it difficult to accept all of the author's conclusions in respect of her otherwise very important discussion of St Andrew's ad clivum Scauri: is it, for instance, necessary to believe that Gregory's dedication of his monastic foundation to St Andrew represented both a conscious identification with the Symmachan faction and a gesture of fraternity with Constantinople, or either? Others more qualified to judge than I will have a view on Müller's analysis of Gregory's pastoral instructions to Augustine at Canterbury. A certain sense of repetition is also created by Müller's recapitulation of her arguments at the end of each of the book's four parts, and then again in the conclusion. One potentially serious problem caused by Müller's chronological approach is the difficulty of integrating the Moralia, Gregory's lengthy commentary on Job (widely considered to be his masterpiece), since Gregory appears to have worked and re-worked this throughout his lifetime. Perhaps, given the nature of the Moralia, we should not underestimate Gregory's desire to impose Konsistenz on himself? In any case, with the exception of the Moralia, these are minor complaints in view of the enlightenment which the reader will find in the work. Of particular interest to this present reviewer is, finally, Müller's discussion of the genesis of Gregory's Dialogues. We are invited (p. 81) ‘to speculate whether Gregory's Dialogues are not also a product of the heated discussions about the saints’ cult' being pursued at Constantinople during his time there as apocrisarius (579–85), although no evidence is produced to support the contention (for which see JECS xvii [2009], 421–57). In brief, researchers will find the work of unquestioned usefulness, particularly when a concise and reliable account of Gregory's individual works – their context, audience and purpose – is desired. As a chronologically ordered companion to Robert Markus' theme-based approach in Gregory the Great and his world (Cambridge 1997), an English translation for the benefit of undergraduates would also be very welcome.