Since at least 1987, when the World Commission on Environment and Development published Our Common Future, sustainability has become an increasingly central concept in redefining environmental stewardship—development that "meets the needs of the present without compromising the ability of future generations to meet their own needs." The march toward realizing the ideal of more responsible stewardship of the earth’s natural resources continues to advance, notwithstanding dramatic changes in the political landscape. In the context of both climate change and the broader sustainability objective, we are witnessing a revolutionary push coming from local governments, nongovernmental organizations, and businesses. This said, a good deal more could be accomplished if sustainability were reduced to a clearer and, ultimately, universally accepted frame serving as a consistent reference for policy development and decisionmaking. Borrowing from NEPA, this Comment proposes a functional working definition of environmental sustainability.