Should there be a human right to a healthy environment? Implicit in the question whether the time has come to consider a right to a healthy environment is the claim that its status as a right hinges on its being incorporated into a formal legal instrument. In line with Sen’s criticism of such a “legally parasitic” view of rights, this chapter argues that a strong case can be made that the aspiration to live in a healthy environment already is a human right. Further, it contends that, even from a purely legal perspective, it can be said that the right is already in existence within customary international law. Finally, it argues that it is useful to reframe the question in the following terms: Should the right be formally adopted in an international legal instrument? Thus restated, the question raises a host of issues regarding efficacy and impact that are common to efforts to turn moral and political claims into legal claims in general, and into international legal claims in particular. Based on an overview of these issues, I answer the question in the affirmative