This symposium will address key, cross-cutting issues of basic ecology that underlie the broader topic of social and environmental sustainability. The core message is that advances in ecological science since 1991, the year ESA announced its Sustainable Biosphere Initiative, have changed ecologists’ perspectives on what exactly is meant by “sustainability” and a “Sustainable Biosphere.” Some of these advances are the product of traditional ecological research, and some are the result of a growing collaboration with social scientists. The Sustainable Biosphere Initiative: An Ecological Research Agenda (Lubchenco et al. 1991, Ecology 72(2)) sought to define the ecological science needed to address the challenge of sustainability and launched ESA’s SBI Office, now the Science Programs Office, in 1992. The premise was that fundamental ecological knowledge and theory were essential to the solution of environmental problems and to achievement of a Sustainable Biosphere. The primary aim was to stimulate ecologists to set clear priorities in basic research and to develop its applications to solution of human problems. In the last 15 years, great progress has been made in defining “Sustainable Biosphere” and in sorting out the essential dimensions of the problem of environmental sustainability and vulnerability. Major developments in basic ecological science have also occurred, including real paradigm shifts that affect how current ecological theory is applied and interpreted. A summary and update of these advances, 15 years after the start of the Sustainable Biosphere Initiative, is timely and appropriate and will help to reinvigorate sustainability science as a long term core activity of ESA. This proposed symposium is particularly appropriate to the theme of the 2007 meeting, “Ecology-based Restoration in a Changing World,” because the goals of restoration are tightly linked to perceptions of the meaning of sustainability and to the intellectual framework in which ecological restoration is judged.