In Living Well Now and in the Future: Why Sustainability Matters, Randall Curren and Ellen Metzger formulate an ethics of sustainability, conceptually connecting sustainability with ongoing opportunities for people to live well. Part of the sustainability ethics they develop is a principle called the Preservation of Opportunity Principle. My goal in this paper is to analyze the Preservation of Opportunity Principle, and amend the principle in light of certain considerations that are not at the forefront of Curren and Metzger’s project. (...) Specifically, I want to develop the principle in a slightly different way given concerns about the noninstrumental value of nonhuman animals, concerns that are integral to a comprehensive environmental ethical theory. (shrink)