This collected volume of fifteen chapters reflects the culmination of a seminar series convened at the University of Oxford between 2009 and 2010, sponsored by the Andrew W. Mellon foundation. The editors are to be congratulated for producing such a coherent and stimulating volume which brings together a diverse collection of papers spanning discussions of the fourth to eighth centuries and encompassing a range of regions stretching from the world of the Late Antique Mediterranean to East Asia and pre-modern China. Individual chapters will be invaluable for researchers with particular specialisms but, for this reviewer, the strength of the volume lies in its comparative approach to the theme of conversion. Byzantinists who choose to read the volume in its entirety will encounter a treasure trove of debate and methodological critique that will prove indispensable for future discussions of the theme.

Conversion as topic of academic conversation is firmly back on the agenda. As Arietta Papaconstantinou succinctly notes in her opening introduction, more recent geo-political events, including the rise of Daesh/Isis, has once more ignited the public debate about conversion as a social phenomenon and the processes and motivations that often underlie it. This interest has, more regrettably, galvanised many of the stereotypes that scholars since the 1970s have consistently worked hard to refute: namely that conversion to Christianity is often seen as a peaceful introspective process, whereas that to Islam is often seen as tempered by more pragmatic motivations, or as a result of violent coercion. Papaconstantinou's swift rebuttal to this model sets the tone of the ensuing volume and usefully draws attention to the distinctive nature of Christian conversion narratives and the problems that have emerged from the adoption of a framework largely based on the Abrahamic faiths in Late Antiquity. A later paper by Max Deeg on Buddhism in East Asia, deals yet another critical blow to the use of ‘conversion’ as a starting line for wider questions about religious change in the Late Antique world. These important qualifications are complemented by the opening essay of Averil Cameron, who addresses the question of Christian conversion in the Late Roman world, a process often problematically addressed within the framework of ‘Christianisation’. This is the most familiar of the themes to historians of Late Antiquity, and Cameron's comments offer a much needed review of the tendency to examine this period as one of linear progression and uniform change. Throughout Cameron's essay, notions of boundaries and permeability are central, and her comments offer a much-needed unpacking of terms and processes that are often mistakenly treated as neatly bounded and static. By drawing attention to the fuzziness of the term ‘Christian’ and the various issues of a rigid-concept ‘conversion’, Cameron signals a number of themes that are taken up in further depth in the other contributions of this volume.

Polymnia Athanassiadi's contribution explores the theme of conversion in the Late Antique world in more depth, highlighting its implications for identity formation and, more importantly, by drawing attention to the multitude of ways in which Christian converts negotiated their conversion and identity within the world of Late Antiquity. A focus on contemporary Mongolia by Vesna Wallace echoes may of the same sentiments, drawing attention to the importance of viewing the process of conversion within a much wider framework of political legislation, intellectual dissemination and competition. The relationship between conversion, rulership and legislation is taken up by further contributions by Simon Corcoran, Antonio Palumbo and Samuel Lieu who individually examine the political implications of a ruler's conversion, yet also ways in which the effectiveness of legislation and the diffusion of religious practice could be tempered and often rendered ineffective by more localised factors.

As noted by many scholars in this volume, conversion narratives and legal legislation are rarely reflections of lived communal boundaries, but works actively engaged in formulating and defining them. Two separate essays by Christopher Kelley and Thomas Sizgorich † explore this particular theme further: Kelley examines episodes of confrontation in the writings of Augustine, and Sizgorich instances of Muslim-Christian interaction in the earliest centuries of Muslim rule. Both authors, however, stress the permeability of these states and the ways in which writers were forced to respond to the ambiguities and frequent transgressions of these imagined boundaries.

The themes of convergence and syncretism are recurring ones in the contributions that follow. Elizabeth Key Fowden's discussion of Christian conversion among the Arabs notes the importance of monastic foundations and the cult of St Sergios in helping to fashion a collective Christian Arab identity. Konstanin Klein's examination of the Life of Hilarion provides a complementary portrait of the fluidity of practices and identifications surrounding the cult of Venus in Elusa. Two studies by Uriel Simonsohn and Moshe Lavee address the question from a different angle, examining how cases of conversion and apostasy are represented in legal and literary texts. In this respect, Simonsohn's observation that conversion was often treated as a communal concern, rather than an individual one, offers a useful corrective to our tendency to view conversion as a discrete and introspective process.

The fifth part of the book breaks with the textual focus of the earlier contributions and addresses the impact of conversion on the material and spatial environment of Late Antique Jerusalem. Jan Willem Drijvers, revisits the complex debate over the emergence of Christianity in Aelia Capitolina. Schick, at the opposite end of the period, traces the continuation of this landscape long after the Arab conquest of the city. Combined, the two reflect how the development of Jerusalem as a ‘Christian’ and eventually ‘Islamic’ city entailed constant negotiation of the histories and associations of the past.

Readers seeking definitive answers to many of the questions raised throughout this volume are unlikely to find them here. Nevertheless, they will come away from this thoughtful and well-constructed volume with a more nuanced appreciation of the debate and the challenges that lie ahead. No scholar interested in the social world of Late Antiquity can afford to ignore it.