Academic discussions about the interethnic relationships operating during the colonial period in Atlantic Patagonia are relatively recent, in contrast with research carried out in the rest of the Argentine Republic. It has resulted in a significant gap—both empirical and epistemological—in the inquiry of the encounter between Europeans and Natives, colonialism itself, and its related materiality in the region. From an historical archaeological approach, the purpose of this chapter is to discuss the agency and the diverse kinds of controls Indigenous groups imposed over the Spanish colonial order established in the Patagonian Atlantic coast of Argentina by the end of the eighteenth century. Interethnic relationships are explored in three study cases from the same colonizing project: Nueva Colonia y Fuerte de Floridablanca (San Julián Bay, Santa Cruz province), the settlement of Real Compañía Marítima (Puerto Deseado, Santa Cruz province), and Fuerte San José and Puesto de la Fuente (Valdés peninsula, Chubut province). Social practices, material conditions of the colonial settlements, and, particularly, the Indigenous perceptions of the colonial outposts are thoroughly considered. This information is intended to display the divergent trajectories of interethnic relationships as well as to approach colonialism in Patagonia from the Natives’ logics and experiences.