If one only read the most prominent selections of World Christianity texts—Andrew Walls’s The Translation Principle in Christian History, or the late Lamin Sanneh’s West African Christianity, for example—one would likely see the assumptions that underlie the field in general: that Christianity is diverse and expanding; that the reasons for its expansion and diversity are due more to the creative agency of non-Euro-American converts than to Western missionaries; and that while the foundation for this growth occurred in the nineteenth century, most of it came to fruition in the late twentieth. If this literature formed the basis of one’s knowledge of Christianity worldwide, then one could be forgiven for not realizing that we are perhaps living through one of the greatest periods of anti-Christian persecution since Christianity’s earliest centuries, as some researchers and activists have claimed.That is because, alongside its many scholarly contributions, the field of World Christianity has also produced some lacunae. It has a difficult time integrating into its narrative those places where Christianity has not thrived. Similarly, we can point to relatively few studies within World Christianity literature that seriously grapple with religious persecution. And the field seems to struggle to construe agency as something other than the production of “new” Christianities, often to the neglect of Christians belonging to traditions whose roots extend well before the nineteenth or twentieth centuries.It is with respect to these three lacunae that we think Under Caesar’s Sword offers a robust and welcome addition to our understanding of contemporary Christianity worldwide. Following their large grant-funded study of the same name, editors Daniel Philpott and Timothy Samuel Shah assembled an impressive collection of contributors who examined how contemporary Christians have responded to persecution. The regions covered read almost like a list of those places most neglected in the World Christianity literature: North Africa and the Middle East, Central Asia, Southeast Asia, and Eastern Europe, though it also includes important contributions on Christians in India, China, and Latin America. The editors are to be commended for the consistently high quality of the essays, as well as for giving due attention to the full swath of Christian denominations and traditions across the regions covered.The responses described in the volume include fleeing, political mobilization, patient nonviolent resistance, international networking, and even armed resistance. Among the contributions, Kathleen Collins’s chapter on Christian repression and survival in post-Soviet Central Asia is particularly enlightening, and Maryann Cusimano Love’s chapter on transnational Christian networks offers important and pertinent data with respect to the ways that Christian persecution has produced various kinds of global imaginings, regional partnerships, and international communities for advocacy and support.The analysis found in Under Caesar’s Sword comes predominantly from sociology and/or political science, and while Christians’ responses are shown to be historically grounded, the chronological scope is mostly quite contemporary. But if one is looking for a political, legal, and institutional introduction to the constraints and structures that impact contemporary Christians in large regions of the world today, as well as how Christians interact with those structures, then Under Caesar’s Sword offers an excellent orientation. In doing so, the volume provides an initial solution to the historiographical dilemma that seems to divide contemporary Christians among those who are agents of religious transformation (e.g., Mark Noll, The New Shape of World Christianity) from those who are victims (e.g., John Allen Jr., The Global War on Christians).Even though Christian responses to persecution is the theme of the volume, one will not find detailed accounts of what Christian faith looks like in these regions—or how Christians’ responses to persecution shape their daily lives, spirituality, theology, or worship. This observation is not so much a criticism of the volume as it is an invitation for scholars of World Christianity to investigate those dimensions of contemporary Christianity worldwide that do not so easily fit with the assumptions of our field.