The Ragguaglio dell’Idolatria del Mondo nuovo is a sixteenth-century manuscript, now preserved in the Biblioteca Nazionale Marciana in Venice. It is a copy of the text – but not of the images – of another famous manuscript in the Vatican Library (BAV, Vat. lat. 3738), known as Codex Vaticanus A or Codex Ríos, which is dedicated to illustrating and describing the religion, history, and culture of various indigenous Mesoamerican peoples. We offer herein the complete transcription of the Ragguaglio, preceded by an introduction that presents the manuscript and emphasizes its importance in terms of understanding the Italian reception of Codex Vaticanus A.