Garry Sparks's recent book examines the interreligious encounters in the highland Maya region of Guatemala during the early decades after Spanish contact. In this volume, intended as a companion to The Americas' First Theologies: Early Sources of Post-contact Indigenous Religion (2017), Sparks presents a theological and intertextual analysis of the Theologia Indorum, or the “Theology for and of the Indians,” presumably written in K'iche’ Maya by the Spanish Dominican friar Domingo de Vico. Completed in 1554 and never published, the Theologia Indorum spanned two volumes and over 800 manuscript pages, becoming the first original theology produced in the Americas. Sparks's assiduous theological and linguistic analysis of the remaining fragments from multiple Theologia Indorum copies uncovers its important role in the transmission of Catholic and Maya religions. Sparks argues that to fully understand its impact, it must be evaluated in relation with contemporaneous religious and legal highland Maya texts, especially the Popol Wuj (1554–58) and the Title of Totonicapán (1554). Sparks demonstrates how Vico, literate K'iche’ Maya intellectuals, and later mendicant priests learned and borrowed from each other to reconfigure highland Maya religious theology.Through careful evaluation of Vico's understudied work and a broader corpus of K'iche’ Maya texts, Sparks focuses on the challenges of translation and the commensurability of ideas between Hispano-Catholic and K'iche’ Maya worldviews. Sparks highlights the diversity of Catholicism in early modern Iberia, which had to be reconciled into the highly localized contexts of the Americas. While Vico's Franciscan counterparts used either Latin or Spanish to present key topics, Vico relied instead on Indigenous terms. Sparks explains Vico's use of K'iche’ Maya linguistic ideology and moral anthropology as evidence of his training in scholastic Thomism, which emphasized the importance of language and the value of analogical reasoning (chapter 2). While the Theologia Indorum was designed for Maya conversion to Catholicism, Vico did not view the two religions as incompatible, nor did he rule out a “mixture of Catholic theology and indigenous culture” in creating the manuscript (p. 162).Sparks traces how Vico and highland Maya intellectuals such as Diego Reynoso reconciled their religions and used Maya terms and images to establish analogies for Catholic concepts. To do so, the volume's first of three parts establishes the “Old World” backgrounds of the highland Maya and Iberian mendicants. Vico's life and work are carefully evaluated in part 2, which provides background on Vico (chapter 3), discusses the Theologia Indorum's structure and creation (chapter 4), and explains his theological method (chapter 5). Through impressive linguistic analysis, Sparks examines how Vico adeptly utilized both the high register (language for ritual speech and elders) and low register (quotidian speech) of K'iche’ Mayan in the Theologia Indorum. By balancing high and quotidian speech and drawing on Maya knowledge, Vico constructed a text that accommodated Maya culture and religiosity. Transcribed or translated over 18 times, the Theologia Indorum became a foundational text in the region, as it was mentioned implicitly or explicitly in many contemporaneous highland Maya writings.In the same way that Vico accommodated Maya religiosity in his work, Sparks reveals how the K'iche’ Maya authors accommodated Vico, as the Theologia Indorum often became synonymous with Christianity in their writings. Part 3 assesses the Theologia Indorum's impact via expert intertextual analysis of contemporaneous K'iche’- and other Mayan-language texts, including the Popol Wuj (chapter 6), the Title of Totonicapán (chapter 7), and other legal writings (chapter 8). Sparks defines these diverse manuscripts as theologies that reveal the various levels of engagement with and responses to the Theologia Indorum by Maya intellectuals. The Title of Totonicapán's authors, for example, took a more conciliatory approach to the Theologia Indorum while also redacting, rather than merely copying, the manuscript in their work. In contrast, the authors of the Popol Wuj presented a slight resistance to Vico by portraying the Theologia Indorum as an “incomplete and deficient” version of the creation story and Maya ancient truths offered by the Popol Wuj (p. 198). Later sixteenth-century writings, however, increasingly saw the Theologia Indorum as an authoritative text and as “truth of God” (p. 297).Sparks's latest work reflects his mastery of the K'iche’ language and offers a welcome addition to the fields of religious studies, ethnohistory, and Maya linguistics. The book contains extensive footnotes and charts comparing the intertextual analysis of the various manuscripts, including a useful “Maya and mendicant intertextual reception history” chart (p. 287). The inclusion of maps could have helped situate readers and further illustrate aspects of the argument, such as the emphasis on locality and the geographical influence of the Theologia Indorum. This is a fascinating, detailed, and insightful work that will be of particular interest to a scholarly audience, as it deepens our knowledge of understudied highland Maya writings and the early evangelization process in Guatemala.