This chapter analyzes the relationship between US foreign relations and the non-human world from the late 1960s through the 1990s in two ways. First, it charts the rise of US international environmental policy. It argues that US leaders often assigned low priority to environmental diplomacy and that non-state actors often played an important role in setting policy agendas, lobbying for policy change, and trying to enforce policy follow through. When leaders did embrace environmental issues, they did so to garner domestic and international goodwill without incurring any additional strategic or financial responsibilities. Yet policymakers struggled to achieve this balance. Environmental diplomacy often exacerbated international tensions over economic, political, and social issues, such as the trade in endangered species in the 1970s to biodiversity conservation in the 1980s to curbing global carbon emissions from the 1990s to the present day.