This chapter examines the history of Marie-Yvonne Vellard, an Aché girl from Paraguay who was captured in the 1930s at the age of two and raised by a French scientist named Jehan Albert Vellard. By examining the various retellings of Marie-Yvonne’s story and the many stories of captured children that populate ethnographic studies of the Aché, this essay tracks how colonial violence against Indigenous peoples was repackaged within a ostensibly antiracist framework. While the redemptive accounts of her story did important work by challenging biological determinism, they also concealed how the practices of mid-century human scientists sometimes encouraged the forced removal of children from their families and the dispossession of Indigenous territory. In fact, as this chapter demonstrates, until the 1960s ethnographic studies of the Aché were based primarily on captured children and attest to an established practice and economy of buying and trading Aché children as servants. Although researchers who studied captured Aché children positioned themselves as civilized men of science, they did not condemn the trafficking of Aché children that they benefitted from and instead presented it as a fait accompli that they could only observe as modest witnesses.