Carlos Galvão-Sobrinho's impressive monograph grapples with a fascinating question: why was the Arian controversy so controversial? The author contends that neither the particular doctrine at stake, nor the new context of a Christian emperor, can satisfactorily explain the unusually extensive and incendiary nature of the dispute. One must look, rather, to the distinctive character of the episcopal response. With a strong emphasis on terminological precision limiting opportunities for theological compromise, and aware that their power and legitimacy were intimately bound up with the ability to demonstrate their ‘orthodoxy’, the bishops ended up adopting a deeply confrontational posture towards their peers. Beginning in Alexandria (but quickly spreading elsewhere), church leaders set about aggressively mobilising support in the public arena, tightening their grip on church communities, and employing violence to further their particular agendas. These new patterns of episcopal behaviour were profoundly to influence the role of the bishop in late antique society. The book is well-structured, and the argument clear throughout. At the heart of the study lies a detailed analysis of the dynamics of the early Arian controversy: the material on the development of the dispute in Alexandria, and on the complex episcopal response to the Council of Nicaea, is especially perceptive. Conceptually, Galvão-Sobrinho builds on the work of Richard Lim (with regard to the nature of public disputation) and Michael Gaddis (on the role of violence in Christian communities), but he also shows himself adept at contributing to more technical debates about chronology (his appendices on the recall of Arius, and on the early career of Athanasius, are thorough and convincing). Occasionally one senses that the desire for a neat thesis triumphs over the messiness of the historical reality: for instance, the argument that the bishops decisively rejected strategies of compromise is not borne out by the evidence of conciliar activity of the 350s, when several attempts were made to achieve consensus through studiously ambiguous or non-controversial formulae. The endnotes are extensive (accounting for a third of the book), but references to primary texts sometimes lack details of the relevant critical apparatus, or unaccountably opt for the Patrologia Graeca when more recent (and superior) editions are available. Indeed, there is no bibliography of ancient sources cited, which is an unfortunate omission. But these are relatively minor gripes. Galvão-Sobrinho's work will be of considerable interest to those working on the dynamics of the fourth-century Church, and will reward close engagement with its arguments. As the author himself notes, the study is, among other things, a perennial reminder that ‘religious piety cannot easily be isolated from love of power’ (p. 158).