This is a choice collection of essays, going beyond all precedent in its close and candid scrutiny of the methods by which ecclesiastical councils in the fourth century produced their decisions on articles of faith. Richard Price sets the tone in the opening study, ‘Conciliar theology: resources and limitations’, in which he argues that florilegia containing the pronouncements of recognised champions of the faith were a useful guide to the definition of heresy, except in the Monothelite controversy, where the testimonies proved rather that there was no fact of the matter worth discussing. Hans Christof Brennecke, in ‘Synoden als Institutionen zwischen Kaiser und Kirche’, concludes that, even when a synod was convened with the aim of bringing about a consensus on terms dictated by the emperor, the interests and convictions of the assembled prelates were strong enough to modify the outcome. As Thomas Graumann observes in ‘Theologische Diskussion und Entscheidung auf Synoden’, historians who perceive that a council's deliberations are not shaped only by theological reasoning tend to follow Edouard Schwartz in ascribing both the event and the outcome to political calculation; a review of the debates inspired by the teaching of Photinus and the Luciferian schism, however, forbids us to doubt the sincerity with which positions were held or the integrity of the procedures by which they were canvassed, defended and at last enforced. The work of Niklas Luhrmann, cited with approbation by Graumann, is the touchstone for Nina Lubomierski's ‘Der Prozess gegen Dioscorus auf den Konzil von Chalcedon’: the Alexandrian patriarch, having assumed the role of autocrat at Ephesus in 449, discovered at Chalcedon that he was facing an indictment rather than a judicial scrutiny, and responded by absenting himself in a manner that prefigures more explicit contestations of legitimacy in modern political trials. The longest contribution is Christian Müller's ‘Die Synode von Mailand 355, Eusebius von Vercelli und die Folgen’, a detailed scrutiny of the letters ascribed to Eusebius of Vercelli and the sparse evidence that survives concerning the causes of his exile, his relations with Athanasius and Liberius and his supposed adherence to the Luciferians. The result is to raise our estimate of his theological acumen and to temper the accusation that his professions of loyalty to the Nicene Creed took on the colour of Lucifer's ‘fanaticism’. Annette von Stockhausen, in ‘Der Brief der Synode der Ankyra 358’, does not pretend to have reached definitive answers in her attempts to parse the texts which Athanasius, Hilary and Epiphanius tendentiously associate with this conclave of their opponents. For all their efforts, modern scholars do not subscribe to a simple polarisation of Nicenes and Arians in the fourth century, and no more, as Uta Heil proves in ‘Was wir wissen und was wir glauben’, did the bishops at Rimini in 359, when they anathematised a number of Arian formulae in the very promulgation which repeated the Council of Sirmium's interdict on the term ousia in 357. Once again the scholarship is exquisite, the conclusions pregnant rather than decisive.