Mining is a key component of both the Brazilian and Chilean economies and accounts for an outsized share of these countries’ exports. Yet, it is a common target for environmental criticism, especially due to its impacts on local populations and ecosystems. Brazil and Chile have adopted markedly different trade strategies over the past three decades, most notably with regards to their involvement in international trade agreements. This paper investigates how these differences in trade policy since 1990 have affected the sustainability of each country’s mining sector by identifying and comparing the channels through which free trade agreements influence the environmental impacts of resource extraction.