Fragments of the Sixteenth-Century Nahuatl Census from the Jagiellonian Library: A Lost Manuscript provides a missing chunk of the sixteenth century Marquesado census—one of the earliest known texts in Nahuatl. In the critical edition of this manuscript, Julia Madajczak, Katarzyna Granicka, Szymon Gruda, Monika Jaglarz, and José Luis de Rojas reveal how it traveled across the Atlantic only to be lost during World War II and then rediscovered at the Jagiellonian Library, Poland. When connected to other surviving fragments of the Marquesado census, now held in Mexico and France, the Jagiellonian Library manuscript sheds new light on pre-contact and early colonial Nahua society. The authors use it to discuss the concept of calpolli, family life, and the production of administrative documentation in the early colonial Tepoztlan of today’s Morelos.