This dissertation traces the debates over the regulation of Indigenous labor in PortugueseAmerica. I follow these debates as they first unraveled in the northeastern sugar-planting regions of sixteenth-century Brazil, and then as they traveled to the State of Maranhão and Grão-Pará, a Portuguese colony in the eastern Amazon that was administered separately from the State of Brazil. I draw from extensive research in multiple imperial archives, with manuscript sources in Portuguese, Spanish, and Dutch, to analyze the development of a school of thought among sectors of the settler population that argued for Indigenous slave-trading and/or increased settler access to Indigenous workers in mission villages. I show how settlers and their opponents manipulated a portfolio of arguments to demand different labor regimes and policies. In their arguments for increased access to Indigenous laborers, settlers claimed that they were poor, that they were dependent on Indigenous skilled labor, that relying on Indigenous workers was more practical than relying on enslaved Africans, and that Indigenous peoples were “práticos na terra,” or experienced in the land, and thus the best-equipped workers in the region. I thus draw attention to the ubiquity of “pragmatic” arguments to labor debates, focusing on how settlers wielded ideas of utility, feasibility, poverty, and the common good, to make their demands. Countering the historiographical assumption that Europeans had a long-standing preference for African enslaved labor, my dissertation argues that Maranhão was a colony where a great variety of ideologies about Indigenous and African peoples were tested, questioned, and reconceptualized across the seventeenth and eighteenth centuries. In particular, Portuguese ideas about Indigenous peoples’ proclivity to work were much more nuanced than the historiography has posited. With time, these arguments became increasingly racialized, as settlers activated ideas about the Indigenous versus the African body and correlated skin color to one’s ability to work. Furthermore, settler arguments demanding greater access to Indigenous laborers often implicitly and explicitly contested the framework of “disease, flight, and capacity to work,” a framework long embraced by the historiography as an explanation for the rise of African slavery in the Americas. In their arguments, settlers in Maranhão wielded their on-the-ground experiences to contend that Indigenous labor was more practical than relying on the trans- Atlantic slave trade, that disease outbreaks justified more slave-trading, and that Indigenous peoples were more apt to the kinds of work required for Amazonian production. Thus, I argue that this framework was as much a constructed argument subject to debate as it was an explanation of a material reality.