Although textiles were important commodities in the Aztec political economy, it is widely held that textile production did not involve organized workshops. In the late 1960s, Charlton (1971, 1981) found a concentration of large spindle whorls at the Aztec city-state capital of Otumba that he interpreted as remains of a maguey-fiber workshop. A subsequent survey and surface collections made by the Otumba Project discovered additional concentrations of spindle whorls associated with fiber-processing tools and manufacturing debris that provide substantial evidence for organized maguey-fiber workshops at Otumba. An unusually large sample of more than 1,600 spindle whorls was recovered in surface collections from sites in the Aztec city-state of Otumba where both small cotton whorls and large maguey whorls occurred in low densities associated with concentrations of domestic pottery (and in some cases house-mound remnants). In the Aztec capital town of Otumba, maguey spindle whorls were also present in localized dense concentrations within a restricted area of the site. These concentrations also included molds for making spindle whorls, “wasters,” a high density of heavily worn obsidian blades and basalt scrapers used in fiber production, and obsidian scrapers. Based on the quantities and types of associated artifacts we argue that these concentrations represent remains of Late Aztec maguey-fiber workshops that were household based. The workshops processed maguey fibers and made maguey spindle whorls in a range of sizes for spinning thin and thick threads and cordage. Secondary craft activities in one workshop included making cotton spindle whorls and some lapidary and figurine manufacturing. Maguey-fiber processing, spinning, and, presumably, weaving also took place in rural villages, but evidence of organized workshops has only been found at the urban center. The growth of the maguey-fiber industry at Otumba during the Late Postclassic period was part of a broader economic trend of production intensification in the northeastern Basin of Mexico that included xerophytic plant cultivation and craft specialization.